2/8 = 1/4, i.e. each meat ball used 1/4 of a pound and he has 3/4 of a pound; therefore, he can make 3 meatballs.
In fractions this is (3/4)/(2/8) = (3/4)/(1/4) = (3/4)* 4 = 3
Remember the rule for division of fractions is invert the denominator and multiply.