The first thing to do is create a common denominator, since this fraction has a common denominator you have to convert the whole numbers to fractions.
3 = 21/7, once you converted 3 to 21/7 add it to 5/7
21/7 + 5/7 = 26/7
1 = 7/7, once you converted 1 to 7/7 add it to 4/7
7/7 + 4/7 = 11/7
26/7 + 11/7 = 37/7, the sum of both converted numbers (26/7 and 11/7) are added
simplify the answer (37/7) to find the final product
5 2/7, 7 goes into 37 five times and the remaining 2 becomes a fraction above 7