If you change 1/4 so that the denominators of both fractions are the same by mutiplying 4x3 for the bottom and 3x1 for the top and then add 5/12 and 3/12 to get 8/12 and then for it to be a whole number, you need 4/12 to complete the whole which is the fraction of children at the bleachers at the basketball game (4/12) .
