Tom goes to a combined undergrad and Ph.D. program. It takes 3 years to finish the BS and 5 years to finish the Ph.D. Tom finishes it in 3/4ths the time. How long does it take for him to finish? Let's be accurate as possible.
The program normally takes 3 + 5 = 8 years. So he manages to finish in 8 * 3 / 4 = 6 years.
The answer: 6.