Help me pls it’s math TwT

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.

What are the coordinates of the point that is 1/3 of the way from a to b? a (2,-3) b (2,6)

Check all that apply. f is a function. f is a one-to-one function. c is a function. c is a one-to-one function.