The reason it is 20% is due to the fact that if you put it in a form showing 250/250 = 100/100 and put another proportional rate underneath it showing 200/250 = x/100, you would have to multiply the numerator of the fraction on the left by the denominator of the fraction on the right to get 20000. Now you divide 250 from 20000 and get x for 80, resulting in 80/100 or 80%. All you have to do now is subtract 100-80, which equals 20, resulting in 20%.
Hope that helps!! It's my first time in answering so, ya. ;D goodluck!
