You work for a store that sells bicycles, tricycle, and tandem bikes. Bicycles have 2 wheels and 2 pedals. Tricycles have 3 wheels and 2 pedals. Tandem bicycles have 4 pedals and 2 wheels. If the store contains 144 bikes of all kinds,378 pedals and 320 wheels, how many bicycle, tricycle, and tandem bikes are in the shop.

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?