Wow. 16,000 a month? Where does he work? Can I come intern?
But anyways, 1/4 of $16000 is $4000 so he has $12,000 left. 3/10 of $12000 is $3600 so he has $8400 left. 5/21 of $8400 is $2000 so therefore he has $6400 left.
Yes it is a function because there are not any repeating x values ( first number in each set of parentheses)
should look about like this