The demand for steak and beef is elastic because there are many substitutes, public transport, petrol and housing are inelastic, and the demand for pencils is monotonic because it is low-priced. Lower the price to get more revenue from sales.
In case of elastic demand, lower the price because in case of elastic demand, a decrease in price causes a relatively large increase in the quantity demanded, thus increasing total revenue. If it is inelastic demand, increase the price to be able to obtain more revenue