Terry earns a base salary of $2100 per month. Once he reaches $40000 in total sales, he earns an additional 5% commission (salary) on the amount of sales over $40000. Let s be the amount of his total sales for the month and M(s) be the amount of his salary for the month. (For instance, if he had sales of $42000 for the month, he would earn a salary of $2100 and 5% of $2000, since $42000 is $2000 more than $40000.)

Step-by-step explanation:

Step one:

given data

we are told that Terry's base salary is $2100  per month.

in addition 5% on sales greater than $40000.

let the monthly salary be M(s)

and let "s" be the amount of sales made

his monthly commission =0.05s

Step two:

The expression for his monthly earning is given as

M(s)=0.05s+2100   where s>40000

 hence for a month when s=42000

M(s)=0.05(42000)+2100

M(s)=2100+2100

M(s)=4200

Therefore for an instance when s=42000 his earnings  for the month will be $4200

4a. is 3 miles every hour

4b. is 1/3 of an hour per mile

step-by-step explanation: