The correct answer is (E) - 13/20
To solve this exercise, first find the smallest common denominator, making the bottom numbers (the denominators) of both fractions, the same. The smallest common denominator is the smallest number that divides by both fractions' denominators. In this case the smallest number that divides by both 5 and 4, is 20.
To turn 2/5 into a fraction whose denominator is 20, multiply both the numerator (2) and the denominator (5), by 4:
(2*4)/(5*4) = 8/20 ;
To turn 1/4 into a fraction whose denominator is 20, multiply both the numerator (1) and the denominator (4), by 5:
(1*5)/(4*5) = 5/20 ;
Now, sum up the fractions:
2/5 + 1/4 = 8/20 + 5/20 = (8+5)/20 = 13/20