Of a certain high school graduating class, 75 percent of the students continued their formal education, and 80 percent of those who continued their formal education went to four-year colleges. If 300 students in the class went to four-year colleges, how many students were in the graduating class?
(A) 500
(B) 375
(C) 240
(D) 225
(E) 180

Let total students in the graduating class be x. .75 x continue with their formal education...
.75x * .80 = .6x go to 4-yr college
.6x = 300
x = 300/.6 = 500