Ryan had some vanilla cookies and chocolate chip cookies. He gave away 100 cookies to his cousin. 10% of them were vanilla cookies and the rest were chocolate chip cookies.

1. How many chocolate chip cookies did he give his cousin?
2. Ryan gave some vanilla cookies to his brother. ⁴₇ of all the cookies he gave away to his cousin and his brother were vanilla cookies. How many vanilla cookies did he give his brother?

(a)
Percentage of chocolate chip cookies
= 100% - 10%
= 90%

Number of chocolate chip cookies that Ryan gave to his cousin
= 90% x 100
= ⁹⁰₁₀₀ x 100
= 90 

(b)
Fraction of all the cookies he gave away to his cousin and his brother that were chocolate chip cookies
= 1 - ⁴₇
= ³₇

3 u = 90

1 u = 90 ÷ 3 = 30

Number of vanilla cookies that Ryan gave to his cousin and his brother
= 4 u
= 4 x 30
= 120

Number of vanilla cookies that Ryan gave to his cousin
= 100 - 90
= 10

Number of vanilla cookies that Ryan gave to his brother
= 120 - 10
= 110

Answer(s): (a) 90; (b) 110