First you need to convert them to the same unit. 1 cm is 10 mm, so the scale is 5:10. 5*2 is 10, so the scale factor is 2.
The answer is 78!
(your speed x how much faster your teacher types)
32.5 x 2.4
Don't understand what you're are asking?
You have to add all the scores and dived by the 20 students, the result is 65.85%
