Which of the following properties is necessary to simplify the expression given below?
(–2) + 5(x – 3) – 4x(6 + 1)

All per-unit concepts rely on ratios, meaning, to provide a type of measurement

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?

If x varies directly as y, and x = 7.5 when y = 10, find x when y = 4