Question

The cost of a toy elephant is the same as the cost of 3 balls. Express the statement as a linear equation in two variables.

Answer 1

Hint: Let the cost of a toy elephant be Rs. x and the cost of a ball be Rs. y. Now, we have to create a linear equation that can express the statement given in the question clearly. Read the question and then form an equation such that the cost of one toy elephant, i.e Rs. x is the same as the cost of 3 balls, i.e Rs. 3y.

Complete step-by-step answer:
For finding the linear equation, first we will have to know what is a linear equation in two variables.
A linear equation in two variables is an equation that can be written as a form $ax+by=c$.
Where x & y are variables and a, b & c are parameters. (or coefficients).
Now, let us assume that the cost of toy elephant = Rs. x and the cost of a ball = Rs. y.
In the question, it is given that the cost of a toy elephant is equal to the cost of 3 balls.
The cost 3 balls $=3\times y=Rs.3y$
The cost of a toy elephant = the cost of 3 balls.
$\Rightarrow x=3y$
And we have to express it in the form of a linear equation.
$\Rightarrow x-3y=0..........\left( 1 \right)$
Equation (1) is the linear equation of the given statement in the question.

Note: The students can make the mistake that they write the equation as $3x=y\ or\ 3x-y=0$ by assuming the cost of the elephant as Rs. x and the cost of the ball as Rs. y, which clearly is wrong. This equation would have been correct if the student had assumed the cost of the elephant as Rs. y and the cost of the ball as Rs. x. We can assume any variable, it is not necessary to assume x and y.