How do I solve this?

Let S(x) represent the total sales (in thousands of (a) The sales at the end of January reached $126,380 dollars) for the month x in the year 2005 at a certain and were rising at the rate of $1900 per month. department store. Represent each statement to the right by an equation involving S or S'. (b) At the end of April, the sales for this month dropped to $30,000 and were falling by about $400 a day. (Use 1 month = 30 days.) (a) Choose the option with equations that best represent (a) above. O A. S(1) = 126.380, S'(1) = - 1.9 O B. S(1) = 1.9, S (1) = 126.380 O C. S(1) = 1.9, S'(1)= - 126.380 OD. S(1) = 126.380, S'(1) = 1.9 (b) Choose the option with equations that best represent statement (b) above. O A. S(4) = 30, S'(4) = -12 B. S(4) = 30, S'(4) = 12 O C. S(4) = 30, S'(4) = 0.4 O D. S(4) = 30, S'(4) = -0.4