using the substitution method what is the answer to this problem, x+3y=7 x+4y=12

Answer 1

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