PSLE
Mr Tang used ⁷₉ of his money to buy 10 mangosteens and 4 starfruits. The cost of 5 mangosteens was the same as that of 2 starfruits. What was the most number of starfruits that Mr Tang could buy with the money he had left?
Fraction of his money that he had left
= 1 - ⁷₉ 
= ²₉

Let the cost of 1 mangosteen be 1 M.
Let the cost of 1 starfruit be 1 S.

5 M = 2 S _(x2)
10 M = 4 S

Since Mr Tang wants to buy starfruits with the money he had left, 10 mangosteens will be substituted as 4 starfruits.

⁷₉ of his money
= 10 M + 4 S
= 4 S + 4 S
= 8 S

⁷₉ of his money → 8 S
¹₉ of his money → ⁸₇ S
²₉ of his money → 2 x ⁸₇ S = 2²₇ S

Maximum number of starfruits he could buy with the money that he had left = 2

Answer(s): 2