I believe A. would be the answer
SORRY IF WRONG
The answer is 11 I hope this helped you
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.

I'm just gonna assume that 6/3 and 1/2 are fractions.
First you have to find common denominators for the fractions to be added.
The first common denominator divisible by both the denominators is 6.
So 2x3=6 and 1x3=3
and 3x2+6 and 6x2+12
so that would be 12/6 + 3/6
Then you would proceed to add both of the numerators together which are 12 and 3.
To get a total of 15/6. You can also simplify that into a mixed number 2 1/2.
Answer:
large truck = 45miles small truck = 60miles
Step-by-step explanation:
180/4 and 180/3