2x-20y=18
-7x+10y=-17

a
multiply 1st equation by __ to set up eliminating x by addition.

b
multiply 2nd equation by __ to set up eliminating x by addition.

c
multiply 1st equation by __ to set up eliminating y by addition.

d
multiply 2nd equation by __ to set up eliminating y by addition

I will try to solve your system of equations−2x−20y=18;−7x+10y=−17Step1: Solve−2x−20y=18 for x:−2x−20y+20y=18+20y  (Add 20y to both sides)−2x=20y+18−2x−2=20y+18−2   (Divide both sides by -2)x=−10y−9
Step 2: Substitute−10y−9 for x in−7x+10y=−17:−7x+10y=−17−7(−10y−9)+10y=−1780y+63=−17 (Simplify both sides of the equation)80y+63+−63=−17+−63 (Add -63 to both sides)80y=−8080y80=−8080 (Divide both sides by 80)y=−1Step 3: Substitute−1 for y in x=−10y−9:x=−10y−9x=(−10)(−1)−9x=1 (Simplify both sides of the equation)x=1 and y=−1