Elisa made more withdrawals because when you divide Elisa's total withdrawal by the amount of cash she withdrew at a time would be 140/20=7. When you compare that to Francis's withdrawal which would be 270/45=6. 7>6 so Elisa made more withdrawals than Francis.
I believe that would be -4.50 for problems like this you subtract then add the negative sign in front i'm surprised you are in high school i did this in 6th grade