gmatt1476 wrote:
In the first 2 hours after Meadow's self-service laundry opens, m large washing machines and n small washing machines are in continual use. Including the time for filling and emptying the washing machines, each load of laundry takes 30 minutes in a large washing machine and 20 minutes in a small washing machine. What is the total number of loads of laundry done at Meadow's self-service laundry during this 2-hour period?
(1) n = 3m
(2) 2m + 3n = 55
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n = the number of small machines
m = the number of large machines
4 = the number of loads in two hrs from a large machine
6 = the number of loads in two hrs from a small machine
(2) gives us an equation for the number of machines, however this equation can be solved in more than one way:
A) if m = 20 (large machines), then n = 5 (small machines)
2*20 + 3*5 = 55 machines
B) if m = 5 (large machines), then n = 15 (small machines)
2*5 + 3*15 = 55 machines
A) gives us a total of 20*4 + 5*6 = 190 loads in two hours
B) gives us a total of 5*4 + 15*6 = 110 loads in two hours
The correct answer must be C?