Help please! I have substituted 25, 17, 13 and -25 from the answer bank - none of which balance out to a -4. Completely stumped.

Hey Janie -- sometimes the formula "looks better" by "putting the negative element on the other side":

5 (x + 3) - (4x - 6) = -4 ... 5(x +3) = (4x -6) -4 ... 5x +15 = 4x -10 ... notice a
**positive** "x" cannot work -- the "5x" side would always "outrun" the "4x" side ...
*only the -25* makes sense ... Best wishes, ma'am :)