The total revenue an advertising company obtains from selling x sports adverts and y food adverts is given by the function Find (a) the MR from selling one additional sports advert, when x = 4 and y =...

The total revenue an advertising company obtains from selling x sports adverts and y food adverts is given by the function

Find

(a) the MR from selling one additional sports advert, when x = 4 and y = 3;

(b) the MR from selling one extra food advert when x = 4 and y = 3.