A certain man works in sales and earns a base salary of $1100 per month plus 5% of his total sales for the month. (a) Explain why his total monthly income I is a linear function of total sales S, both measured in dollars. The change in I is always the same, dollar , for a 1 dollar increase in S. (b) How much does he earn if he sells $1400 in merchandise in a month? (Round your answer to the nearest cent.) $ (c) Write a formula that gives total monthly income I as a linear function of sales S in a month. (Round equation parameters to two decimal places.) I= (d) What should his monthly total sales be if he wishes to earn $1300 this month? (Round your answer to the nearest cent.) $ CRAUDCOLALG6 3.R.009. Consider the following data. (a) Test the data to see whether they are linear. linear not linear (b) Make a linear model for the data. f(x)=