working out the cost of something using a ratio

Question

White paint costs £2.80 per litre.

Blue paint cost £3.50 per litre.

White paint and blue paint are mixed in the ratio of 3:2.

 

Work out the cost of 18 litres of the mixture

Answer 1

3x +_ 2x = 18

5x = 18

x = 3.6

 

White is 3(3.6) liters

Blue is 2(3.6) liters

 

Can you calculate the cost of each and answer?