to add these you must have a common denominator. In this case 10 will work because both 5 and 10 can evenly go into 10. Now whatever you multiplied the bottom by to get 10 you must do the same to the top. This is shown below:
3/5+ 1/10 = 6/10+ 1/10
You can now add these together to get 7/10. This is also in the simplest form.