The average speed is given by:
average speed=(total distance)/(total time)
total time for the first 30 miles was:
time=distance/speed
=30/30
=1 hr
total time for the remaining 30 miles
=30/60
=0.5
hence the average speed will be:
speed=(30+30)/(1+0.5)=60/1.5=40 miles per hour
5 .This is called the greatest common factor.
You can list all the factors(ways to divide) of each number and find the biggest one.
15'1,3,5,15
10'1,2,5,10
The greatest they share is 5
