Workers at a building site have the option to eat lunch provided by an outside company. When the price per lunch is R40, there is a dermand for 80 lunches. It is known that for each R5 increase in price, demand decreases by three lunches. Determine the demand function for lunches with quantity dernanded (Q) as a function of price (P).
A. Q = 104 - 0, 6P
B. Q = 56 + 0, 6P
C. Q = 136, 67 - 0, 67P
D. Q = 40 - 3/5P