PSLE
Mr Peh used ³₇ of his money to buy 12 mangosteens and 10 chikoos. The cost of 4 mangosteens was the same as that of 2 chikoos. What was the most number of chikoos that Mr Peh could buy with the money he had left?
Fraction of his money that he had left
= 1 - ³₇ 
= ⁴₇

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

4 M = 2 C _(x3)
12 M = 6 C

Since Mr Peh wants to buy chikoos with the money he had left, 12 mangosteens will be substituted as 6 chikoos.

³₇ of his money
= 12 M + 10 C
= 6 C + 10 C
= 16 C

³₇ of his money → 16 C
¹₇ of his money → ¹⁶₃ C
⁴₇ of his money → 4 x ¹⁶₃ C = 21¹₃ C

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

Answer(s): 21