PSLE
Mr Yong used ³₈ of his money to buy 6 chikoos and 9 mangosteens. The cost of 3 chikoos was the same as that of 2 mangosteens. What was the most number of mangosteens that Mr Yong could buy with the money he had left?
Fraction of his money that he had left
= 1 - ³₈ 
= ⁵₈

Let the cost of 1 chikoo be 1 C.
Let the cost of 1 mangosteen be 1 M.

3 C = 2 M _(x2)
6 C = 4 M

Since Mr Yong wants to buy mangosteens with the money he had left, 6 chikoos will be substituted as 4 mangosteens.

³₈ of his money
= 6 C + 9 M
= 4 M + 9 M
= 13 M

³₈ of his money → 13 M
¹₈ of his money → ¹³₃ M
⁵₈ of his money → 5 x ¹³₃ M = 21²₃ M

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

Answer(s): 21