Form the pair of linear equations for the following problems and find their solution by substitution method. (i) The coach of a cricket team buys 7 bats and 6 balls for Rs.3800. Later, she buys 3 bats and 5 balls for Rs.1750. Find the cost of each bat and each ball.(ii) The taxi charges in a city consist of a fixed charge together with the charge for the distance covered. For a distance of 10 km, the charge paid is Rs 105 and for a journey of 15 km, the charge paid is Rs 155. What are the fixed charges and the charge per km? How much does a person have to pay for travelling a distance of 25 km?
Form the pair of linear equations for the following problems and find their solution by substitution method. (i) The coach of a cricket team buys 7 bats and 6 balls for Rs.3800. Later, she buys 3 bats and 5 balls for Rs.1750. Find the cost of each bat and each ball.(ii) The taxi charges in a city consist of a fixed charge together with the charge for the distance covered. For a distance of 10 km, the charge paid is Rs 105 and for a journey of 15 km, the charge paid is Rs 155. What are the fixed charges and the charge per km? How much does a person have to pay for travelling a distance of 25 km?

Arrangement (i):

 

Let the expense a bat be x and cost of a ball be y.

 

As per the inquiry,

 

\[7x\text{ }+\text{ }6y\text{ }=\text{ }3800\text{ }\ldots \text{ }\ldots \text{ }\ldots \text{ }.\text{ }\left( I \right)\]

\[3x\text{ }+\text{ }5y\text{ }=\text{ }1750\text{ }\ldots \text{ }\ldots \text{ }\ldots \text{ }.\text{ }\left( II \right)\]

 

From (I), we get

 

\[y\text{ }=\text{ }\left( 3800-7x \right)/6\ldots \text{ }\ldots \text{ }\ldots \text{ }\ldots \text{ }..\left( III \right)\]

Subbing (III) in (II). we get,

\[3x+5\left( 3800-7x \right)/6\text{ }=1750\]

 

$\Rightarrow 3x+\text{ }9500/3-35x/6\text{ }=1750$

 

\[\Rightarrow 3x-35x/6\text{ }=\text{ }1750-9500/3\]

 

\[\Rightarrow \left( 18x-35x \right)/6\text{ }=\text{ }(5250-9500)/3\]

 

\[\Rightarrow -17x/6\text{ }=\text{ }-\text{ }4250/3\]

 

\[\Rightarrow -17x\text{ }=\text{ }-\text{ }8500\]

 

 

\[x\text{ }=\text{ }500\text{ }\ldots \text{ }\ldots \text{ }\ldots \text{ }\ldots \text{ }\ldots \text{ }..\text{ }\left( IV \right)\]

 

 

Subbing the worth of x in (III), we get

 

\[y\text{ }=\text{ }\left( 3800-7\text{ }\times 500 \right)/6\text{ }=\text{ }300/6\text{ }=\text{ }50\]

 

 

Consequently, the expense of a bat is Rs 500 and cost of a ball is Rs 50.

 

Arrangement (ii):

 

Leave the decent charge alone Rs x and per km charge be Rs y.

 

\[x\text{ }+\text{ }10y\text{ }=\text{ }105\text{ }\ldots \text{ }\ldots \text{ }\ldots \text{ }..\text{ }\left( 1 \right)\]

 

\[x\text{ }+\text{ }15y\text{ }=\text{ }155\text{ }\ldots \text{ }\ldots \text{ }\ldots \text{ }..\text{ }\left( 2 \right)\]

 

 

From (1), we get

\[x\text{ }=\text{ }105\text{ -}10y\text{ }\ldots \text{ }\ldots \text{ }\ldots \text{ }.\text{ }\left( 3 \right)\]

 

 

Subbing the worth of x in (2), we get

 

$105\text{ – }10y\text{ }+\text{ }15y\text{ }=155$

 

\[5y\text{ }=\text{ }50\]

 

\[y\text{ }=\text{ }10\text{ }\ldots \text{ }\ldots \text{ }\ldots \text{ }..\text{ }\left( 4 \right)\]

 

 

Placing the worth of y in (3), we get

 

\[x\text{ }=\text{ }105\text{ -}10\text{ }\times \text{ }10\text{ }=\text{ }5\]

 

Thus, fixed charge is Rs 5 and per km charge = Rs 10

 

Charge for

\[25\text{ }km\text{ }=\text{ }x\text{ }+\text{ }25y\text{ }=\text{ }5\text{ }+\text{ }250\text{ }=\text{ }Rs\text{ }255\]