First of all, as with every question, we need to write down the information we have. so we know that y is 20% bigger than x meaning y=1.2x. this is because to increase x by 20% you need to multiply by 1.2 which is effectively giving 120% of the value. therefore we can see that for every one y that we have, we also have two 1.2 x's. therefore the ratio is 1:1.2, remember 1.2 can be written as 6/5 therefore we have 1:6/5. to get rid of the fraction we can multiply both sides by 5 to get the ratio of y to x as 5:6.