Paint is red : blue in a ratio 2: 4. if 5 litres of red is used, how much blue?

So since the ratio of red paint to blue paint is 2:4 and you can simplify 2:4 into 1:2 and because 5 liters of paint is used you would have to multiply the 2 from the simplified ratio by 5 so you could get the answer 2*5 and that equals 10

Red = 2 = 5 liters

blue = 4 = 10 liters

10 liters of blue is used