Fiona spent 70% of her money on a number of cards. She spent 20% of the remaining money on a few stamps and 50% of what was left on a number of erasers.

1. What fraction of her money was left?
2. Given that the cards cost $58 more than the erasers, find the sum of money Fiona had at first.

(a)
70% = ⁷⁰₁₀₀ = ⁷₁₀

Fraction of money left after buying the cards = 1 - ⁷₁₀ = ³₁₀

20% = ²⁰₁₀₀ = ¹₅

Fraction of remaining money after buying the stamps = 1 - ¹₅ = ⁴₅ 

50% = ⁵⁰₁₀₀ = ¹₂

Fraction of what is left after buying the erasers = 1 - ¹₂ = ¹₂

Fraction of money left after buying the cards
= ³₁₀ x ⁴₅ x ¹₂
= ³₂₅

(b)
Fraction of money spent on the erasers
= ³₁₀ x ⁴₅ x ¹₂
= ³₂₅

Fraction of money spent on the cards
= ⁷₁₀
= ³⁵₅₀

Amount spent more on the cards than the erasers
= 17.5 u - 3 u
= 14.5 u

14.5 u = 58

1 u = 58 ÷ 14.5 = 4

Amount that Fiona had at first
= 25 u
= 25 x 4
= $100

Answer(s): (a) ³₂₅; (b) $100