Solve the system of equations by substitution

Question

Use the system of equations shown

3x+4y=-9

9x+2y=3

Answer 1

multiply 1st equation by 3 to get

9x +12y = -27, then subtract the 2nd equation to get

10y = -30, divide by 10

y = - 3

3x=-9 -4y = -9 +12 = 3

x = 1

x=1, y =-3 is the solution