 # Every six months, price of petrol increases at the rate of ₹4 per litre

(i) Every six months, price of petrol increases at the rate of ₹4 per litre. Taking price of petrol in December, 2011 as x and in December 2012 as y, form a linear equation showing amount spent on petrol in December 2012.
(ii) Due to continuous rise in the petrol price, people are shifting towards CNG whose price increases at the rate of ₹ 3 per litre in a year. Form a linear equation taking price of CNG in December 2011 as a and in December 2012 as b.
(iii) Which fuel will you prefer and why?
(iv) Which value is depicted by using CNG
over petrol?

(i) Given, price of petrol in December 2011 =₹ x
and price of petrol in December 2012 = ₹ y
Since, every six months, price of petrol increases at the rate of ₹4 per litre.
Then, by given condition, y = x + 8
which is the required linear equation.
(ii) Given, price of CNG in December 2011 =₹ a
and price of CNG in December 2012 =₹ b
Since, every year the price of CNG increases at the rate of ₹ 3 per litre.
Then, by given condition, b = a + 3
which is the required linear equation.
(iii) CNG, because CNG is cheaper than petrol and
control the pollution.
(iv) Environmental protection.