One scale factor equation is y=cx y is the new factor (in this case, 60 or 75) c is the scale factor (in this case, unknown) x is the old factor (in this case, 24 or 30) so: plug in the values 60=c(24) divide both sides by 24 c=2.5
you can check again with the other numbers 75=c(30) divide both sides by 30. c= 2.5