Question

Every six months, price of petrol increases at the rate of Rs 4 per litre. Taking price of petrol in Dec, 2011 as x and present price of petrol as y, form a linear equation showing amount spent on petrol in Dec, 2011. Also, due to continuous rise in the petrol price, people are shifting towards CNG whose price increases at the rate of Rs 3 per litre in a year. Form a linear equation taking price of CNG in Dec, 2011 as a and in Dec, 2012 as b.

Answer 1

(i) As price of petrol increases Rs.4 per month, hence it increase 8 by every year
Now duration from 2011 December to 2017 December is 6 years.
incraese in price in 6 year=8*6=Rs.48
price in 2011 dec=x
price in 2017 dec=y=x+48

(ii) Price of CNG increases at the rate of Rs 3 per litre in a year.
duration between 2011 dec and 2012 is 1.
price of CNG in dec 2011=a
price of CNG in dec 2012=b=a+3