Level
It takes Machine L and Machine B 50 minutes to print a total of 3150 copies of brochures. Machine L can print 30 copies of brochures in one minute. How many copies of brochures can Machine M print per minute?
Level 3
A typist can type 60 words per minute. For every 120 words, 4 words are typed wrongly. At this rate, how many words are typed correctly in 6 minutes?
Level 2
Water is leaking from a tank measuring 125 cm by 84 cm by 110 cm at a rate of 3.5 ℓ per minute. After 5 hours, the tank is empty. What was the depth of water in the tank at first?