To answer the ratio, massage this equation around to find ' n/m ' .
Let's subtract 'm' from each side:
4n = 2n + 7m
Subtract '2n' from each side:
2n = 7m
Divide each side by 'm' :2 (n/m) = 7
Divide each side by 2 :
n/m = 7/2 . . . . . there's your ratio. That's choice-'e'.