Riordan had some cheese muffins and chocolate chip muffins. He gave away 200 muffins to his sister. 20% of them were cheese muffins and the rest were chocolate chip muffins.

1. How many chocolate chip muffins did he give his sister?
2. Riordan gave some cheese muffins to his brother. ³₅ of all the muffins he gave away to his sister and his brother were cheese muffins. How many cheese muffins did he give his brother?

(a)
Percentage of chocolate chip muffins
= 100% - 20%
= 80%

Number of chocolate chip muffins that Riordan gave to his sister
= 80% x 200
= ⁸⁰₁₀₀ x 200
= 160 

(b)
Fraction of all the muffins he gave away to his sister and his brother that were chocolate chip muffins
= 1 - ³₅
= ²₅

2 u = 160

1 u = 160 ÷ 2 = 80

Number of cheese muffins that Riordan gave to his sister and his brother
= 3 u
= 3 x 80
= 240

Number of cheese muffins that Riordan gave to his sister
= 200 - 160
= 40

Number of cheese muffins that Riordan gave to his brother
= 240 - 40
= 200

Answer(s): (a) 160; (b) 200