1. You need to change these so that they share a common denominator (bottom of the fraction)
2. Common denominator is 10 of these 2 fractions.
3. We don't need to change the 7/10 fraction because the denominator is already 10.
4. To make 1/2 have a denominator of 10, we need to times the top and bottom by the same number. To get 10 from 2, we have to times it by 5. Therefore, to change the top, we need to times it also by 5
5. 1 x 5 = 5
6. Add the two fractions together: 5/10 + 7/10 = 12/10
7. Simplify the expression. This is currently a top heavy fraction aka. improper fraction. To make it 'proper' we need to change it into a mixed number. To do this, we see how many of the bottom number goes into the top. In this case it is 1 with 2 left over. So the final fraction is...
1 2/10
Hope this helps :)