James pays $1000 for advertising.  It brought 100 customers to his site and 80% of those bought something at the store that cost $25.  How much profit does he gain from the ad?
100*.8=<<100*.8=80>>80 customers bought something
That means they were worth 80*25=$<<80*25=2000>>2000
So he gained 2000-1000=$<<2000-1000=1000>>1000 from the ad
#### 1000