m is an unknown number that is being decreased by 7.
OPTION A IS WRONG BECAUSE MATHEMATICALLY IT IS WRITTEN AS

B IS WRONG BECAUSE IT MEANS

C IS WRONG BECAUSE IT MEANS

BUT D IS THE ANSWER BECAUSE IT MEANS

SINCE m IS TREATED AS AN UNKNOWN NUMBER.
GOODLUCK!!!!
8*a=32
32:8=a
4=a
4+26=b
30=b
X - 14 = 52
move - 14 for + 14
x = 52 + 14
x = 66