Subject: mathqa
Question: circular gears l and r start to rotate at the same time at the same rate . gear l makes 20 complete revolutions per minute and gear r makes 60 revolutions per minute . how many seconds after the gears start to rotate will gear r have made exactly 8 more revolutions than gear l ?
Option: 
A: a ) 6
B: b ) 8
C: d ) 14
D: e ) 12
Answer: D