Plz answer all 4 please i really need help or i will get in trouble

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.

Kevin's bank offered him a 4.5% interest rate for his mortgage. if he purchases 3 points, what will be his new rate?

The relative growth rate for a certain type of fungi is 60% per hour. a small culture has formed and in just 6 hours the count shows to be 20,273 fungi in the culture. what is the initial number of fungi in the culture?