Do you add 16 = -4 in this equation? 3x3 + 7 = -3 - 1 When I add it I get = 12

This doesn't make any sense

LHS=16

RHS=-4

Like Aziz said 16 is not equal to -4 

Note that 16 does not equal -4 so you cannot add 4 to both sides to get 20...