Question

2z - 31 = -9z + 24

can anyone tell me how to know if we must subtract or add? like we must write it as this when we solve it 2z - (- 9z) or 2z + -9z

Answer 1

you move one of the equations to the other side and then combine like terms

Answer 2

you would combine like terms so the answer would be -7z-7