3. the shutter speed ,s, of a camera varies inversely as the square of the aperture setting, f,. when f=8, s=125..
a) find a formula for s in terms of f.

b) hence, or otherwise, calculate the value of s when f=4.
i need now
maths

1. what are the missing reasons in the proof 2. it's in the second picture and 3

You buy a veido game for $60 and the sales tax is 8% what is the total cost for the game including the sales tax

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?