Im sure you have your answer by now but would you mind posting the answer
Cleo would be 193 years old when Clara turns 38
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.

Answer:
It all depends.
Step-by-step explanation:
It depends on what you are trying to do, and what you want to solve for. If you are trying to distribute the 3 into 2, you would place the parentheses around the 2. I hope I was able to help, but there is not much that I can do without more clear instructions!