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.

It would be $2.40. 4 or less just ignore 5 or more add 1 more
Answer: 15x+12
Step-by-step explanation: This expression is already simplified :( You can reverse the coefficients though! Both will still be equal, but you can’t simplify anymore.