Yes they are the both equal 5.25 when divided
Answer: 
Step-by-step explanation:
Given
New mail carrier takes 4 hours for delivery i.e.
New mail carrier completes
part of work in 1 hour
Old mail carrier takes 3 hours for delivery i.e.
mail carrier completes
part of work in 1 hour
If they work together, they complete the work in x hours i.e.

The product would expand to

This is a trinomial, and the only way to make it a binomial is to cancel out a coefficient using our variable
.
So, we can cancel either the linear term or the constant term.
In the first case, we require

In the second case, we require

But
must be a non-zero rational number, so this solution is not feasible.