If i dropped a short heavy knife out of a airplane flying at an altitude of 18,000 ft, how long would it take to hit the ground

Ineed asap. i cant understand this question i need someone to me right away

Marco has $38.43 dollars in his checking account. his checking account is linked to his amazon music account so he can buy music. the songs he purchases cost $1.29. part 1: write an expression to describe the amount of money in his checking account in relationship to the number of songs he purchases. part 2: describe what the variable represents in this situation.

Which of the choices shown could be used to prove that aacp=abcp ?