There were some apples, starfruits and mangosteens. The number of apples was four times the number of starfruits. The total number of apples and starfruits was half of the number of mangosteens. There were 180 fruits altogether. All the mangosteens were sold at 8 for $13. How much money was collected from the sale of the mangosteens?
Number of starfruits = 1 u
Number of apples = 4 u

Total number of starfruits and apples
= 1 u + 4 u
= 5 u

Number of mangosteens
= 2 x 5 u
= 10 u

Total number of fruits
= 1 u + 4 u + 10 u
= 15 u

15 u = 180

1 u = 180 ÷ 15 = 12

Number of mangosteens sold
= 10 u
= 10 x 12
= 120

Number of sets of 8 mangosteens
= 120 ÷ 8
= 15

Amount collected from the sale of mangosteens
= 15 x 13
= $195

Answer(s): $195