A water tank holds 675 gallons but is leaking at a rate of 4 gallons per week. A second water tank holds 900 gallons but is leaking at a rate of 7 gallons per week. After how many weeks will the amount of water in the two tanks be the same? The amount of water in the two tanks will be the same in weeks.

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?