Madam Aminah baked some cookies to sell. $\frac{3}{4}$ of them were cream cookies and the rest were plain cookies. After selling 210 plain cookies and $\frac{5}{6}$ of the cream cookies, she had $\frac{1}{5}$ of the cookies left. How many cookies did Madam Aminah sell altogether? Ans: ___

1. Find the fraction of the total cookies that were cream cookies sold.

Fraction of cream cookies sold = $\frac{5}{6} \times \frac{3}{4} = \frac{5}{8}$

2. Find the fraction of the total cookies that corresponds to the plain cookies sold.

Fraction of plain cookies sold = $1 - \frac{5}{8} - \frac{1}{5} = \frac{40}{40} - \frac{25}{40} - \frac{8}{40} = \frac{7}{40}$

3. Calculate the total number of cookies baked.

$\frac{7}{40}$ of total cookies = $210$
Total cookies = $210 \div 7 \times 40 = 1200$

4. Calculate the total number of cookies sold.

Fraction of cookies sold = $1 - \frac{1}{5} = \frac{4}{5}$
Total cookies sold = $\frac{4}{5} \times 1200 = 960$