3.2-5.7=-2.5 so its have to be a negative because a smaller number subtract a bigger number have to be equal to a negative number.
2/3 + 1/4. You start by converting the fractions so that they have a common denominator.
8/12 + 3/12 = 11/12
11/12 of the girls have blue and brown eyes. That leaves 1/12 of the girls who have neither blue nor brown eyes.