How do you solve:

5x+6y=15

y=-4x-7

by the substitution method

5x+6y=15

y=-4x-7

To solve this, I would first substitute - 4x-7 for y

5x+6 (-4x-7) = 15

Then distribute the terms in the 6 (-4x-7) part

5x+-24x-42=15

Then simplify

-19x-42=15

Then add 42 to both sides

-19x=57

Divide - 24 to both sides

x=57/-19 or - 3

Then y=-4 (-3) - 7

y=12-7

y=5