Uzanne can work 10 math problems in 15 minutes. how many can she work in an hour and a half?

1 and half hour
= 60 minutes+ 30 minutes
= 90 minutes

Now,

Uzanne need 15 minutes to do 10 problems
Uzanne need 1 minute to complete 10/15 problems

Uzanne need 90 minutes to do
= (10/15)*90
=(2/3)*90
=2*30
=60 problems

The answer would be a i think