Please I need helpll

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.

How to find the exponential function y=ca^x, with points (1,2) and (2,1)

[tex]a + (3a - 2b) - (4a - 3b)[/tex]whats the answer to this ? ?