First find a common denominator.
Multiply 2 to both numerator and denominator of 2/7
(2/7)(2/2) = 4/14
Combine
4/14 + 3/14 = 7/14
Note that 7/14 can be simplified. Divide 7 from numerator and denominator.
7/14 = 1/2
1/2 is your answer
hope this helps