Well first you would set up your ratio, 17/x = 35/100. You are trying to find x. To do so you cross multiply and divide. So first you have 17× 100 which equals 1700. The you divide that number by 35 which is around 48 like you said. I usually just round to the hundredths place so just cut it at 48.57 but to be safe say approximately 48.57