Keanu mixes 4 litres of blue paint with 3 litres of yellow paint to make purple paint. How many litres of yellow paint should he add to 12 litres of blue paint so that the colour is the same?
Just write the numerals down as an answer.
4 blue/3 yellow = 12 blue/x yellow
divide out the units
4/3 = 12/x
4x = 36
x = 9 <--------- litres of yellow paint
check: ratio of original, blue : yellow = 4 : 3
ratio of new can : blue : yellow = 12 : 9 = 4 : 3
good mix