Question

Carla always sorts her M&M's before eating them. One Day she noticed that 2/5 of of them were red, 1/4 of them were brown,3/10 of them were green, and that 10 of them were yellow.

How many total M&M's?
How many were red?
How many were brown?
How many were green?

Answer 1

1- (2/5+1/4+3/10) : 10
1 : x
Cross multiply:
x=10*1/(1- (2/5+1/4+3/10))

I get 200.

That's a lot of M&M, Carla had better have a good dentist!