please help me
A salesperson earns a base salary of $4000 per month plus 15% commission on sales. her monthly income f(s) is given by the function f(s)=4000 +0.15s where s is monthly sales in dollars use this information for numbers 9-11

9) find g(s) if the salesperson's commission is lowered

10) find h(s) if the salesperson's base salary is doubled

11) find k(s) if the salesperson's base salary is cut in half and her commission is doubled