What is the equation for this problem? In a den are three lamps of equal size , a radio that uses one-third the number watts used by a lamp , and a heater that uses fifteen times as many watts as a lamp when all are in use the total electrical power is 1.1 kilowatts how many watts does the radio use? (1 kilowatt=1,000 watts)

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?