There were some starfruits, lemons and oranges. The number of starfruits was two times the number of lemons. The total number of starfruits and lemons was one-third of the number of oranges. There were 180 fruits altogether. All the oranges were sold at 5 for $6. How much money was collected from the sale of the oranges?
Number of lemons = 1 u
Number of starfruits = 2 u

Total number of lemons and starfruits
= 1 u + 2 u
= 3 u

Number of oranges
= 3 x 3 u
= 9 u

Total number of fruits
= 1 u + 2 u + 9 u
= 12 u

12 u = 180

1 u = 180 ÷ 12 = 15

Number of oranges sold
= 9 u
= 9 x 15
= 135

Number of sets of 5 oranges
= 135 ÷ 5
= 27

Amount collected from the sale of oranges
= 27 x 6
= $162

Answer(s): $162