Maria burns about 600 calories per hour jogging and about 450 calories per hour biking if Maria spends x hours per day biking and 4/5 as much time jogging which of the following functions best models the amount of calories C that Maria burns in one day form jogging and biking A) C(x) =840x
B) C(x) = 930x
C) C(x) = 960x
D) C(x) =1050x

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?