Snap, Crackle, and Pop spend $150 on cereal in a grocery store.  Snap spends twice as much as Crackle.  Crackle spends 3 times as much as Pop.  How much did Pop spend?
Let x represent the amount that Pop spent in $
Crackle: 3x
Snap:2(3x)=6x
x+3x+6x=150
10x=150
x=15
#### 15