5x+2y=7.

4x+y=8

Systems of equations substitution method

y = - 4 substitution

x=3 and y=-4

Step-by-step explanation:

Solve4x+y=8for y:

4x+y=8

4x+y+-4x=8+-4x (Add - 4x to both sides)

y=-4x+8

Step: Substitute-4x+8 for y in 5x+2y=7:

5x+2y=7

5x+2 (-4x+8) = 7

-3x+16=7 (Simplify both sides of the equation)

-3x+16+-16=7+-16 (Add - 16 to both sides)

-3x=-9

-3x/-3=-9/-3

(Divide both sides by - 3)

Step 2: Substitute 3 for x in y=-4x+8:

y=-4x+8

y = (-4) (3) + 8

y=-4 (Simplify both sides of the equation)