1. In this expression, which is the variable? 5 + y a. P
b. 5
d. +
с. у
2. What is the variable in the expression 16r - 3?
b. R
d. 3
a.
C. -
3. What is the variable in the expression y - 7?
Y b. -
d. Z
c. 7
4.
What are the variables in the expression 10z?
a. Y b. Z
d. +
c. 10
5. Evaluate the expression 4 + d when d = 100
a. 400
b. 104 c. 4
d. 1,004

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?