Put the steps in order that are used to solve the following systems of equations by substitution.

−7x−2y=−13

x−2y=11
(10 points)

responses
-16y - 77 = -13
-7 (2y+11) - 2y = -13
-16y = 64
x - 2y = 11 --> x = 2y + 11
x- 2 (-4)=11
-14y - 77 - 2y = -13
(3, -4)
x + 8 = 11
x = 3
y = -4

3 answers

To solve the system of equations by substitution, the steps can be arranged in the following order:

  1. Start with the second equation and solve for x:

    • \( x - 2y = 11 \) → \( x = 2y + 11 \)
  2. Substitute x into the first equation:

    • \(-7(2y + 11) - 2y = -13\)
  3. Distribute and simplify the equation:

    • \(-14y - 77 - 2y = -13\) → \(-16y - 77 = -13\)
  4. Combine like terms:

    • \(-16y = 64\)
  5. Solve for y:

    • \(y = -4\)
  6. Substitute y back into the equation for x:

    • \(x - 2(-4) = 11\)
  7. Solve for x:

    • \(x + 8 = 11\) → \(x = 3\)
  8. State the final solution as an ordered pair:

    • \((3, -4)\)

Putting this all together, the ordered steps are:

  1. \(x - 2y = 11 \Rightarrow x = 2y + 11\)
  2. Substitute: \(-7(2y + 11) - 2y = -13\)
  3. Distribute: \(-14y - 77 - 2y = -13\)
  4. Combine terms: \(-16y - 77 = -13\)
  5. Solve for y: \(-16y = 64\)
  6. Substitute: \(x - 2(-4) = 11\)
  7. Solve for x: \(x + 8 = 11\)
  8. Final solution: \((3, -4)\)
A company owns two dealerships, both of which sell cars and trucks. Dealership A sells a total of 164 cars and trucks. Dealership B sells twice as many cars and half as many trucks as Dealership A, and sells a total of 229 cars and trucks.

(4 points)
a) An equation for the total cars and trucks for Dealership A: (response area 1)

b) An equation for the total cars and trucks for Dealership B: (response area 2)

c) How many cars did Dealership A sell? (response area 3)

d) Considering that Dealership B sold half as many trucks as Dealership A, how many trucks did Dealership B sell? (response area 4)

1 responses
x + y = 229
x + y = 393
x + y = 164

2 responses
1/2x + 1/2y = 229
2x + 1/2y = 229
1/2x + 2y = 164

3 responses
132
98
196
66

4 responses
33
66
49
98

To solve this problem, we'll first define \( x \) as the number of cars sold at Dealership A and \( y \) as the number of trucks sold at Dealership A.

a) An equation for the total cars and trucks for Dealership A:

Since Dealership A sells a total of 164 cars and trucks, the equation is:

  • Response Area 1: \( x + y = 164 \)

b) An equation for the total cars and trucks for Dealership B:

Dealership B sells twice as many cars as Dealership A could be expressed as \( 2x \) and half as many trucks as Dealership A could be expressed as \( \frac{1}{2}y \). Since the total sales at Dealership B is 229 cars and trucks, the equation is:

  • Response Area 2: \( 2x + \frac{1}{2}y = 229 \)

c) How many cars did Dealership A sell?

We can solve the system of equations:

  1. \( x + y = 164 \) (Equation for Dealership A)
  2. \( 2x + \frac{1}{2}y = 229 \) (Equation for Dealership B)

From the first equation, we can express \( y \) in terms of \( x \):

  • \( y = 164 - x \)

Now substitute \( y \) into the second equation:

  • \( 2x + \frac{1}{2}(164 - x) = 229 \)
  • Simplifying gives: \( 2x + 82 - \frac{1}{2}x = 229 \) \( \frac{4x - x}{2} + 82 = 229 \) \( \frac{3x}{2} + 82 = 229 \) \( \frac{3x}{2} = 229 - 82 \) \( \frac{3x}{2} = 147 \) \( 3x = 294 \) \( x = 98 \)

So Dealership A sold:

  • Response Area 3: \( 98 \)

d) Considering that Dealership B sold half as many trucks as Dealership A, how many trucks did Dealership B sell?

Since Dealership B sells half the number of trucks as Dealership A, we will first find the number of trucks sold by Dealership A:

  • From \( y = 164 - x \)
  • \( y = 164 - 98 = 66 \) (trucks sold at Dealership A)

Dealership B sells half of this:

  • Trucks sold by Dealership B: \( \frac{1}{2}y = \frac{1}{2}(66) = 33 \)

So, Dealership B sold:

  • Response Area 4: \( 33 \)

Summary of Responses:

  • Response Area 1: \( x + y = 164 \)
  • Response Area 2: \( 2x + \frac{1}{2}y = 229 \)
  • Response Area 3: \( 98 \) (cars sold by Dealership A)
  • Response Area 4: \( 33 \) (trucks sold by Dealership B)