The answer is x= -3
The explanation if you need it is since m(x)=13 we get the equation 13=-2x+7. Then we use the equation to find x.
13= -2x+7
-7 -7
6= -2x
— —
-2 -2
-3=x
You then want to check your answer by substituting -3 for x
13= -2(-3) +7
13= 6+7
13=13
If your answers match then your answer is correct
