Question

Solve the system of linear equations by substitution. y=−3x−7 y=x+9

Answer 1

x+9=-3x-7

add 7 to both sides

x+16=-3x

subtract 1x from both sides

16=-4x

divide both sides by -4

-4=x

y=x+9

y=-4+9

y=5

check:

5=-3(-4)-7

5=12-7

5=5

so

x=-4

y=5