John has $80. Every week, he spends $7. Create an equation that represents how much money, m, he has after t weeks.
How much money, in dollars, will he have after the fourth week?
Enter the equation and the answer on separate lines.

How to use order of operation in 20 divide by 4 multiply 5 = 1

What function has a range {yly< 5}? question on picture above^

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?