please answer quickly! Carolyn makes and sells necklaces. The material to make each neckalce costs $3.20. She has 12 necklaces to sell and wants to make a total profit of $54. The following equation describes the situation.
Carolyn found that x = 7.7 and determined that she will make a profit of $7.70 on each necklace . Which error did Carolyn make?

The solution means that she should charge $7.70 for each necklace.
The solution means that each necklace costs $7.70 to make.
The solution to the equation is not x = 7.7.
Carolyn did not distribute the parentheses when solving.

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?