Tropical Storm Sally brings 3 days of rain to southern Texas.  The first day it rained 4 inches.  The second day it rained 5 times as much as the first day, and the third day it rained 6 inches less than the sum of the first two days.  How much did it rain on the third day?
First Day:<<4=4>>4 inches
Second Day: 5(4)=20 inches
Third Day: (4+20)-6=<<(4+20)-6=18>>18 inches
#### 18