Please help!
ten points and brainless answer!

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.

Identify the initial amount a and the growth factor b in the exponential function. a(x)=680*4.3^x

Will mark brainliest for correct answer! i have been on this problem for an hour and can't find the answer. i'm begging here! incase you cant read the instructions in the picture because of too much or too little lighting: note: enter your answer and show all the steps that you use to solve this problem in the space provided.write a list of steps that are needed to find the measure of b. provide all steps as clear as possible, !