Question

Use substitution to solve the equation.

4x - y = 15
-2x + 3y = 12

Answer 1

y=4x-15
-2x+3(4x-15)=12
-2x+12x-45=12
10x=57
x=57/10
y=39/5

Answer 2

4x - y = 15
Solve for y:
-y = 15 - 4x
y = -15 +4x

-2x + 3y = 12
-2x + 3(-15 +4x) = 12
-2x -45 +12x = 12
10x = 57
x = 57/10 **

y = -15 +4x
y = -15 + 4(57/10) = -15 + 114/5 = -75/5 + 114/5 = 39/5 ***

(57/10 , 39/5)
Decimals: (5.7, 7.8) *****