PLEASE HELP
1) A business rents cars for $120 a day and vans for $250 a day. One day it rented a total of 21 vehicles and made $3300. How many cars and vans were rented?

2) A business rents cars for $120 a day and vans for $250 a day. One day it rented a total of 21 vehicles and made $3300. How many cars and vans were rented?

3)Flying against the wind, a plane travels 2800 km in 4 hours. Flying with the wind it travels 4000 km in 5 hours. What is the rate of the plane in still air and what is the rate of the wind?