Question

3x = -y + 12
2x + 3y = -6

Answer 1

3x=-y+12

2x+3y=-6

collecting the like terms we have

3x+y=12

2x+3y=-6

to solve this simultaneous equation, we use substitution method

we make y the subject in equation one:

y=12-3x

then we put y=12-3x into 2x-3y=-6 in equation two

2x+3(12-3x)=-6

2x+36-9x=-6

-7x+36=-6

-7x=-6-36

-7x=-42

x=-42÷-7

x=6

then we put x=6 in y=12-3x:

y=12-3x

y=12-3(6)

y=12-18

y=-6