7th grade Math! Help and Explain if you can!

Peaches cost $4.29 per pound. find the cost of two and a quarter pounds of peaches.

Astuntman jumping off a 20-m-high building is modeled by the equation h=20-5t^2, where t is the same in seconds. a high-speed camera is ready to film him between 15m and 10m above the ground. for which interval of time should the camera film him?

What are the domain and range of the function f(x)=2^x+1