PSLE
Mr Choy used ⁵₇ of his money to buy 12 persimmons and 8 mangosteens. The cost of 4 persimmons was the same as that of 2 mangosteens. What was the most number of mangosteens that Mr Choy could buy with the money he had left?
Fraction of his money that he had left
= 1 - ⁵₇ 
= ²₇

Let the cost of 1 persimmon be 1 P.
Let the cost of 1 mangosteen be 1 M.

4 P = 2 M _(x3)
12 P = 6 M

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

⁵₇ of his money
= 12 P + 8 M
= 6 M + 8 M
= 14 M

⁵₇ of his money → 14 M
¹₇ of his money → ¹⁴₅ M
²₇ of his money → 2 x ¹⁴₅ M = 5³₅ M

Maximum number of mangosteens he could buy with the money that he had left = 5

Answer(s): 5