Ruby has a goal to save $170 by the end of the summer. She has already saved $50, and is selling drawings she has made for $10 each. How many drawings does she need to sell to save exactly $170?

Question

Let d be the number of drawings Ruby sells. Start by writing an expression that represents the total amount of money Ruby has after selling d drawings.
Good work!
Complete the equation to represent the amount of money Ruby wants to save.
10d+50 =
Nice!
Solve for the value of d. Solve on paper, or show your work below. Then enter your answer on Zearn.
10d+50
=
170

d
=
Great job!
What does your answer of 12 mean in this situation?
10d+50 = 170
d = 12

Ruby needs to sell 12 drawings in order to save $170.

Ruby needs to sell the drawings for $12 in order to save $170.

Ruby needs to make $12 more to save $170

Answer 1

Let's go through the steps you've outlined and clarify everything.

1. Expression for Total Savings: Ruby wants to save a total of $170. She has already saved $50. If she sells \( d \) drawings at $10 each, her total money saved can be expressed as: \[ 10d + 50 \]

2. Equation for Savings Goal: To express the condition where Ruby's total savings equals her goal of $170, we set up the equation: \[ 10d + 50 = 170 \]

3. Solving for \( d \):

   • Start by subtracting 50 from both sides: \[ 10d = 170 - 50 \] \[ 10d = 120 \]
   • Now, divide both sides by 10: \[ d = \frac{120}{10} \] \[ d = 12 \]

4. Interpretation of \( d = 12 \): The solution of \( d = 12 \) means that Ruby needs to sell 12 drawings in order to save exactly $170.

The statements provided in the last part are slightly misphrased:

• "Ruby needs to sell 12 drawings in order to save $170." (This is correct and reflects the meaning of our solution.)
• "Ruby needs to sell the drawings for $12 in order to save $170." (This is incorrect; each drawing sells for $10, not $12.)
• "Ruby needs to make $12 more to save $170." (This is also incorrect; she needs to sell 12 drawings to make an additional $120, not just $12.)

So, the correct interpretation is: Ruby needs to sell 12 drawings in order to save $170.