how to subtract

6 3/10 - 4 11/15

You need to put the fractions with a common denominator, and "borrow" 1 from the integer of the number 6 3/10 and add it to the fraction, so that it has a larger fraction than the other number. That changes it to 5 13/10. Then subtract the integers and the fractions separately.

In other words

5 13/10 - 4 11/15 =
5 39/30 - 4 22/30 =
1 17/30