Will mark BRAINLIEST. Where did the -3 come from? (Photo attached)

Answer:
-3 is just the answer of the equation.....you must solve x so turn it into 1x and solve it.....plz mark me brainliest
Step-by-step explanation:
Step-by-step explanation:
die to the fact that in the parabolas calculation the X's cancel each other out
so the equation is below the -2 etc
as -2+(-4) is -6
therefore -6/2 is -3