PSLE
Mr Sih used ³₁₀ of his money to buy 15 mangoes and 7 persimmons. The cost of 5 mangoes was the same as that of 2 persimmons. What was the most number of persimmons that Mr Sih could buy with the money he had left?
Fraction of his money that he had left
= 1 - ³₁₀ 
= ⁷₁₀

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

5 M = 2 P _(x3)
15 M = 6 P

Since Mr Sih wants to buy persimmons with the money he had left, 15 mangoes will be substituted as 6 persimmons.

³₁₀ of his money
= 15 M + 7 P
= 6 P + 7 P
= 13 P

³₁₀ of his money → 13 P
¹₁₀ of his money → ¹³₃ P
⁷₁₀ of his money → 7 x ¹³₃ P = 30¹₃ P

Maximum number of persimmons he could buy with the money that he had left = 30

Answer(s): 30