posted by Jon .
I chose C
4m/5n^2 - n/2m
4m/5(n)^2 - n/2(m)
You need to find a common denominator for the two fractions you are trying to subtract. Simplifying the problem:
A/B - C/D = (A*D-C*B)/(B*D)
In this case,
Substituting this into the simplified equation gives:
(8m^2-5n^3)/(10n^2m) which is answer (A)
A clue to the correct answer is that (A) and (B) are only a little different, so it's probably one of them!