Train a and train b leave a central station at the same time. they travel the same speed, but in opposite directions, with train a heading towards station a, and train b heading towards station b. train a reaches station a after 2 1/2 h. train b reaches station b after 4 h. station a and b are 585 mi apart.
what is the rate of the trains?

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?