12x-8y+3y-7x+5y x=5 y+7
12x-8y+3y-7x+5y
x=5
y+7
60 - 56 + 21 - 35 + 35 = 25
12x - 8y + 3y - 7x + 5y 12 * 5 - 8 * 7 + 3 * 7 - 7 * 5 + 5 * 7 60 - 56 + 21 - 35 + 35 = 25
12*5 - 8*7 + 3*7 -7*5+ 5*7= 60-56+21-35+35=25