Question

Solve the system of equations
3x-4y=40
5x-5y=55
1.(14,3)
2. (18,7)
3.(4,-7)
4.(8,-3)

Answer 1

To solve the system of equations, we can use either the substitution method or the elimination method.

Using the substitution method:
From the first equation, we can rearrange it to solve for x:
3x - 4y = 40
3x = 4y + 40
x = (4y + 40)/3

We can substitute this expression for x into the second equation:
5x - 5y = 55
5((4y + 40)/3) - 5y = 55
(20y + 200)/3 - 5y = 55
20y + 200 - 15y = 165
5y = -35
y = -7

Substituting the value of y back into the expression for x:
x = (4(-7) + 40)/3
x = -28/3 + 40/3
x = 12/3
x = 4

Therefore, the solution to the system of equations is (4, -7).

Comparing this solution to the given options, the correct answer is option 3.(4,-7).