Question

Please help! Which of the following is a solution to the system of two equations y = 3x - 7 and 4x - 5y = -20?

a.) (5,8)

b.) (10,12)

c.) 2,-1)

d.) 9,20)

Answer 1

a

Explanation:

y = 3x - 7 → (1)

4x - 5y = - 20 → (2)

substitute y = 3x - 7 into (2)

4x - 5(3x - 7) = - 20

4x - 15x + 35 = - 20

- 11x + 35 = - 20 ( subtract 35 from both sides )

- 11x = - 55 ( divide both sides by - 11 )

x = 5

substitute x = 5 into (1)

y = 3(5) - 7 = 15 - 7 = 8

solution is (5, 8 )