So in the question:1/10 + 3/5, the fractions do not have common denominators. So to add them you must make them common denominators. In the fraction 3/5, 5 is the denominator and can go into ten twice. So you multiply the top and bottom of the fraction by 2: 3•2=6 and 5•2 =10. Your new fraction is 6/10. 6/10 +1/10 is 7/10.
