Answered

There are



80
students in a speech contest. Yesterday,



1

4
of them gave their speeches. Today,



2

5
of the remaining students gave their speeches. How many students still haven't given their speeches?



Answer :

diene
yesterday, 1/4 of 80 =20 gave their speeches, so there are 80-20=60 students left.
Today, 2/5 of 60=24 students gave their speeches, so there are 60-24=36 students who still haven't give their speeches
another way to think of it is 80*(1- 1/4)*(1- 2/5)=80*(3/4)*(3/5)=36