The answer for this question is that the remaining amount fencing left
after Alan has completed his garden will be 3 4/5 yards. This can be
worked out, by first determining that the overall amount of fencing Alan
used was 5.9 + 10.3, to create a total of 16.2. The remaining amount of
fence can therefore be calculated by subtracting 16.2 from 20 to get
3.8 yeards. As a fraction this would then by written as 3 8/10, which
can then be simplified down to get your answer of 3 4/5.