Question

Solve the following system of equations by Substitution. 5x + 4y = 7 -2x - 2y = 8

Answer 1

Answer:

y = 9/13

Step-by-step explanation:

x = -4 + y

5(-4 + y) + 4y = 7

-20 + 9y = 7

9y = -13

Answer 2

Answer:

5x + 4y = 7 × -2

-2x - 2y = 8 × 5

-10x - 8y = -14

-10x - 10y = 40

Step-by-step explanation:

2y = -54 ÷2

y = -27

Now substitute the value of y into equation (1)

5x + 4y = 7

5x + 4(-27) = 7

5x = 7 + 108

5x = 115

X = 23