There are 9 students in the school choir. The ratio of girls to boys in the choir is 5 : 4. Two girls are absent from practice on Monday. What is the ratio of girls to boys at choir practice on Monday? A. 3 : 4

B. 5 : 2

C. 9 : 8

D . 10 : 7

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?