Final answer:
The original price of petrol is found by solving the equations xy = 1740 and (x + 2)(y - 1) = 1740. The increase in petrol prices is often a result of supply and demand imbalances, and saving petrol can involve more efficient driving and shared transportation modes.
Step-by-step explanation:
To find the original price of petrol, let's assume the original price per litre is Rs. x. At this price, the person can buy y litres of petrol with Rs. 1740, so the equation would be xy = 1740. Now, if the price increases by Rs. 2, the new price is x + 2 and the person can buy one litre less for the same amount of money, so the equation becomes (x + 2)(y - 1) = 1740. Solving this system of equations, we find the values of x and y which give us the original price and the amount of petrol bought initially.
Discussing why the price of petrol is increasing and how to save it reflects on economic principles. When the price is above the equilibrium, as in the example where it increases from $1.40 to $1.80, the quantity demanded decreases as people adjust to use less petrol. A rise in prices typically happens because of factors like increased demand, reduced supply, or higher production costs. To save petrol, one might consider driving more efficiently, maintaining the vehicle in good condition, using public transportation, or opting for carpooling.