请教：郁闷，另一道PREP里看不懂的题：（

WillNmind

Working along at its own constant rate, a machine seals k cartons in 8 hours, and working along at its own constant rate, a second machine seals k cartons in 4 hours. If the two machines, each working at its own constant rate and for the same period of time, together sealed a certain number of cartons, what percent of the cartons were sealed by the machine working at the faster rate?

25% / 33.3% / 50% / 66.6% / 75%   Ans: D

giji_78

(k/4)/（k4+k8）

WillNmind

多谢，还是语文功底不够啊~