Answer:
C.
Step-by-step explanation:
I'm assuming that the equation is (1+n) / 7 = 3, where 1+n is the numerator and 7 is the denominator.
In this case, to isolate for n, you have to multiply both sides by 7.
then you get 1+n = 3/7, and then you can get n = 3/7 - 1