It takes me 20 minutes to walk from home to the bus station. I catch the bus from the bus station to work each morning. My bus journey is 10 miles and usually takes 30 minutes. I can catch a bus at 20 minutes past the hour or 10 minutes to the hour. When I get off the bus, it takes me 5 minutes to walk to work.
a) What is the average speed of the bus?
b) I have to be at work for 8:30. What time for the latest I can leave home to be at work on time?
My working out:
10 miles = 0.5h
Speed: 10 / 0.5 = 20mph
How would I use that to work out b?
Thank you and help is appreciated
From bus stop to work you need $30+5=35$ minutes. If we subtract $35$ minutes from $8:30$ we get $7:55$. There is $7:50$ bus which you can catch if you leave house at $7:30$.