Question

Dave and Mary depart from the bus station at 10 am traveling in opposite directions. Dave's bus is going 40 miles per hour and Mary's is going 50 miles per hour. At what time will they be 270 miles apart?

When you work this problem, you get t = 3. Your teacher requires your answer in a complete sentence. What is your answer?
A) The buses will be 270 miles apart at 1 PM.
B) The buses will be 270 miles apart at 1 AM.
C) The buses will be 270 miles apart at 12 AM.
D) The buses will be 270 miles apart at 12 PM

Answer 1

Let in t hours, they are at 270 miles apart .

After t hours, Dave traveled

$=40 t \ miles$

And Mary traveled ,

$=50t \ miles$

So the equation is

$40t+ 50t = 270 \\ 90t = 270 \\ t= 3 hours \ from \ 10am$

That is at 1 pm, they are 270 miles apart. And the correct option is A .