Two mechanical shafts are joined together at their ends. Together their total is 18 and 2/9 ft. if one shaft is 13 and 4/7 ft long , how long must the other shaft be?

Answer 1

18 2/9
-13 4/7

The common denominator is 63

2(7)/63 for the first fraction
9(4)/63 for the second fraction

14/63 - 36/63

you cannot subtract the 36 from 14

You have borrow one from the 18
the 18 becomes 17 + 1 or 17 +63/63

Now, your problem becomes
17 77/63
-14 36/63

can you finish from here? remember to reduce the fraction to lowest terms if needed.

Answer 2

4 31/63