How do I solve this problem?

Question

A tour bus normally leaves for its destination at 5:00 p.m. for a 260 mile trip. This week however, the bus leaves at 5:40 p.m. To arrive on time, the driver drives 8 miles per hour faster than normal. What is the normal speed of the bus?

Answer 1

Say, the normal speed is =x mph

Time taken with this normal speed =260/x.   hours

 

The driver drives later 8 mph faster

ie speed =(x+8). mph

Time taken =260/(x+8).  hours

So,

(260/x)  -  (260/(x+8) =40/60

 

Solve the above equation

 

x= 52 mph

Normal speed =52 mph