Tammy had some money. She spent 10% on food and 25% of her remaining money on a skirt. She had $108 left.

1. How much did she have at first?
2. If the skirt was bought at a 20% discount, what was the original price of the skirt?

(a)
Percent of Tammy's amount left after she spent on food
= 100% - 10%
= 90%

Percent of Tammy's remaining amount left after she spent on the skirt
= 100% - 25%
= 75%

Fraction of Tammy's amount left
= 75% x 90% 
= ⁷⁵₁₀₀ x ⁹⁰₁₀₀
= ²⁷₄₀

Total amount that Tammy had = 40 u
Amount that Tammy had left = 27 u

27 u = 108

1 u = 108 ÷ 27 = 4

Amount that Tammy had at first
= 40 u
= 40 x 4
= $160

(b)
Fraction of Tammy's amount spent on the skirt
= 25% x 90% 
= ²⁵₁₀₀ x ⁹⁰₁₀₀ 
= ⁹₄₀

Amount that Tammy spent on the skirt
= 9 u
= 9 x 4
= $36

Discounted price of the skirt in percent
= 100% - 20%
= 80%

80% of the price of the skirt = 36
1% of the price of the skirt = 36 ÷ 80 = 0.45
100% of the price of the skirt = 100 x 0.45 = 45

Original price of the skirt = $45

Answer(s): (a) $160; (b) $45