Multiply each fraction by each others denominator and see if they match.
For example for the first one ->
7/10 + 1/2 multiply the numerator and denominator of 1/2 by 10 (the bottom of the other fraction) and you get 10/20. The. The bottom of 1/2 is 2, so 2 times 7/10 is 14/20. So 14/20 + 10/20 is equal to the first one.
