Elisa takes a maximum of 6 guitar lessons each month. She is required to rent a guitar for a one-time rental fee of $20 and each lesson costs $45. If Elisa takes x lessons, the total cost of guitar lessons she takes in a month can be represented by the function f (x)= 20 + 45x. What is the range of the function?

Aspacecraft can attain a stable orbit 300 kilometers above earth if it reaches a velocity of 7.7 kilometers per second. the formula for a rocket's maximum velocity v in kilometers per second is vequalsminus0.0098tplusc ln upper r, where t is the firing time in seconds, c is the velocity of the exhaust in kilometers per second, and r is the ratio of the mass of the rocket filled with fuel to the mass of the rocket without fuel. find the velocity of a spacecraft whose booster rocket has a mass ratio of 20, an exhaust velocity of 2.1 km/s, and a firing time of 15 s. can the spacecraft achieve a stable orbit 300 km above earth?