Okay, first find a common denominator for 3 1/5 and 3 3/10.
The one I have is 10.
So, change 3 1/5 to 3 2/10 and keep 3 3/10 the way it is.
The answer could be either 3 2/10 or 3 3/10.
Now for explaining, just write what I wrote to you in your own words.