There were some mangoes, oranges and starfruits. The number of mangoes was three times the number of oranges. The total number of mangoes and oranges was one-quarter of the number of starfruits. There were 180 fruits altogether. All the starfruits were sold at 4 for $7. How much money was collected from the sale of the starfruits?
Number of oranges = 1 u
Number of mangoes = 3 u

Total number of oranges and mangoes
= 1 u + 3 u
= 4 u

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

Number of sets of 4 starfruits
= 144 ÷ 4
= 36

Amount collected from the sale of starfruits
= 36 x 7
= $252

Answer(s): $252