using the substitution method what is the answer to this problem, x+3y=7 x+4y=12
x + 3 y = 7 Subtract 3 y to both sides
x + 3 y - 3 y = 7 - 3 y
x = 7 - 3 y
Put x = 7 - 3 y into equation x + 4 y = 12
7 - 3 y + 4 y = 12
7 + y = 12 Subtract 7 to both sides
7 + y - 7 = 12 - 7
y = 5
Replacing y = 5 into x = 7 - 3 y gives
x = 7 - 3 * 5
x = 7 - 15
x = - 8