So our ratio is 2:3, therefore we are looking for a multiple of 2 and a multiple of 3 that are proportional to this ratio. We can start by multiplying the ratio by 2, which gets us 4:6, which, since 4+6 is ten, is not a correct answer. If you continue the pattern of multiplying the ration with different numbers, you would eventually discover that, if you multiply the ratio by 5, you get 10:15. Since 10+15 is equal to 25, we know that this is the correct answer