7.There are 400 couples competing in a dance contest. After each half hour one-fourth of the contests-ants are eliminated. How many couples will remain eligible fore the prize after the first hour?

A.300
B.250
C.225
D.200
E.150

Well, in 1 hour, there are 2 eliminations . 1/4 of 400=100. 400-100=300. 1/4 of 300= 75. 300-75= 225. Hope this helps!