The car hire charges in a city comprise of a fixed charges together with the charge for the distance covered. For a journey of 12 km, the charge paid is Rs. 89 and for a journey of 20 km, the charge paid is Rs. 145. What will a person have to pay for travelling a distance of 30 km?

Given:

The car hire charges in a city comprise of a fixed charges together with the charge for the distance covered. For a journey of 12 km, the charge paid is Rs. 89 and for a journey of 20 km, the charge paid is Rs. 145.

To do:

We have to find the amount to be paid for travelling a distance of 30 km.

Solution: 

Let the fixed charge and the additional charge be $x$ and $y$ respectively.

According to the question,

$x + 12y = 89$.....(i)

$x + 20y = 145$.....(ii)

Subtracting equation (i) from equation (ii), we get,

$(x+20y)-(x+12y)=145-89$

$x-x+20y-12y=56$

$8y=56$

$y=\frac{56}{8}$

$y=7$

Substituting $y=7$ in equation (ii), we get,

$x+20(7)=145$

$x+140=145$

$x=145-140$

$x=5$

The fixed charge is Rs. 5 and the charge for every km is Rs. 7.  

 The total charge for a journey of 30 km $=x+30y$

$=5+30(7)$

$=5+210$

$=215$

Therefore, the person has to pay Rs. 215 for travelling a distance of 30 km.