addition of equations

Question

trying to understand how to add 5x-9y=1 and -7x+2y=-5

Answer 1

-2x-7y=-4

just add like terms, add the x terms, add the y terms add the constant terms

5-7 =-2 for the x terms

-9+2 = -7 for the y terms

1+(-5) = -4 for the constant terms