Problema Solution
Working together Rosa and Anne can plant 20 flats of pansies in 3 hours. If Rosa works alone, it takes her 8 hours longer than it takes Ann to plant all 20 flats. How long does it take Rosa to plant the pansies by herself?
Answer provided by our tutors
20/3 flats per hour is the together rate of Rose and Anne
x = the number of hours that Ann needs to finish the job alone, x>0
20/x flats per hour is the rate of Ann
x + 8 = the number of hours that Rosa needs to finish the job alone
20/(x + 8) flats per hour is the rate of Rosa
20/x + 20/(x + 8) = 20/3
........
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x = 4 hr
x + 8 = 4 + 8 = 12 hr
It takes 12 hours for Rosa to plant the pansies by herself.