Devon earns a base salary of $600.00 per month, plus a 4% commission on his sales. Last month he brought in $15,000.00 in sales. Write an expression to represent his total compensation and calculate how much his total compensation was.

.4(600+s); $6,240
600+.04s; $1200
.04(600+s); $624
600+.4s; $6,600