Question

white paint costs £2.80 per litre. blue paint costs £3.50 per litre. white paint and blue paint are mixed in the ratio 3:2. work out the cost of 18 litres of the mixture

Answer 1

There are five parts to the ratio:
18 ÷ 5 is 3.6.
Therefore you need 10.8l of white paint and 7.2l of blue paint.

10.8l * 2.80 = £30.24
7.2l * 3.50 = £25.20

The total is £55.44