2a+6=12 what does a =

For a field trip to the zoo, 4 students rode in cars and the rest filled nine busess. how many students were in each bus if 472 students were on the trip

Jonathan can type 20 documents in 40 minutes ,and susan can type it in 30 minutes and jack can type it in 24 minutes working together ,how much time will it is take them type the same document

Tanyss's house has 25 windows. her brother has washed 22 of the windows. what percent of the windows has her brother washed?