Q. P, Q and R are three typists who working simultaneously can type 216 pages in 4 hours. In one hour, R can type as many pages more than Q as Q can type more than P. During a period of five hours, R can type as many pages as P can during seven hours. How many pages does each of them type per hour?

1. 14, 17, 20
2. 15, 18, 21
3. 15, 17, 22
4. 16, 18, 22