PSLE
Mr Song used ⁴₉ of his money to buy 15 pomegranates and 5 starfruits. The cost of 5 pomegranates was the same as that of 4 starfruits. What was the most number of starfruits that Mr Song could buy with the money he had left?
Fraction of his money that he had left
= 1 - ⁴₉ 
= ⁵₉

Let the cost of 1 pomegranate be 1 P.
Let the cost of 1 starfruit be 1 S.

5 P = 4 S _(x3)
15 P = 12 S

Since Mr Song wants to buy starfruits with the money he had left, 15 pomegranates will be substituted as 12 starfruits.

⁴₉ of his money
= 15 P + 5 S
= 12 S + 5 S
= 17 S

⁴₉ of his money → 17 S
¹₉ of his money → ¹⁷₄ S
⁵₉ of his money → 5 x ¹⁷₄ S = 21¹₄ S

Maximum number of starfruits he could buy with the money that he had left = 21

Answer(s): 21