(i) `Q_(d) =40-5p`. Putting the value of price (i.e. Rs. 2), We get : `Q_(d) = 40 - 5xx 2 = 30` units
(ii) Putting the value of demand (0), we get , `0= 40 - 5p`. It means, p = Rs. 8. At price of Rs. 8, demand will be zero
(iii) Putting the value of price (0), we get :
`Q_(d) = 40 - 5 xx 0 = 40` units. At demand of 40 units, price will be zero.