Both lines are being cut by the same transversal so to solve for x, we have to make both equations equal to each other( 2x+10 = 3x-15) isolate x or 3x ( the inverse operations ). Add 15 to 10 (10+15=25) which turns into 2x+25=3x. Combine the x values (25=3x-2x) which results in 25=1x. Divide both sides to complete the problem, which would give you x=25