There were some starfruits, pears and lemons. The number of starfruits was three times the number of pears. The total number of starfruits and pears was one-quarter of the number of lemons. There were 180 fruits altogether. All the lemons were sold at 8 for $8. How much money was collected from the sale of the lemons?
Number of pears = 1 u
Number of starfruits = 3 u

Total number of pears and starfruits
= 1 u + 3 u
= 4 u

Number of lemons
= 4 x 4 u
= 16 u

Total number of fruits
= 1 u + 3 u + 16 u
= 20 u

20 u = 180

1 u = 180 ÷ 20 = 9

Number of lemons sold
= 16 u
= 16 x 9
= 144

Number of sets of 8 lemons
= 144 ÷ 8
= 18

Amount collected from the sale of lemons
= 18 x 8
= $144

Answer(s): $144