A cake recipe uses flour and sugar in the ratio $5 : 2$ by weight. Sunita has 900 g of flour and 300 g of sugar. If she keeps the ratio exact, what is the most flour she can use?

Explanation

1. 01

   Using all 900 g of flour would need $900 \times 2/5 = 360$ g of sugar, but she has only 300 g.

2. 02

   So sugar is the limit: flour = $300 \times 5/2 = 750$ g.