Convert both mixed numbers to improper fractions since they do not have a similar denominator.
2 7/10 becomes 27/10
1 1/4 becomes 5/4
Now you need to find the least common denominator that 10 and 4 go into which is 20.
Multiply the top and bottom by the number it takes to make the denominator in each fraction 20
27/10 becomes 54/20 because you multiply the 10 and 27 by 2.
5/4 becomes 25/20 because you multiply the 4 and 5 by 5.
Now you can subtract the two fractions:
54/20 - 25/20 = 29/20
29/20 can be reduced to 1 9/10 which is how much farther he must go.
