you must first find a common denominator, in which would be 10. For the fraction 2/5 you would multiply it by 2. whatever you do to the denominator you must do to the numerator so you would come out with 4/10. you would take the second fraction 1/2 and multiply it by 5 in the denominator and numerator to get 5/10. you would than add the numerators of 4/10 and 5/10 to get the answer of 9/10. your final answer would be 9/10