3a. every morning, halle goes to school with a 1 liter bottle of water. she drinks one fourth of the bottle before school starts and two thirds of the rest before lunch. what fraction of the bottle does halle drink after school starts, but before lunch?

3b. how many milliliters are left in the bottle at lunch?

Mat bought a phone for $100. he has to pay $30 per mouth. if he has paid $640 in total, how many mouth has he had the phone?

The function show two sisters' savings account and the rate at which they plan to deposit money

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?