Question

The cost of 12 chairs and 15 tables is Rs. 58,968. What is the cost of 4 chairs and 5 tables?
(A) Rs. 19,656
(B) Rs. 29,484
(C) Rs. 39,312
(D) Rs. 40,672

Answer 1

Hint:Assume the cost of a chair as x and cost of table as y. The cost of 12 chairs and 15 tables is Rs. 58,968. In terms of mathematical equations we can write it as, \[12x+15y=58968\] . We have to find the cost of 4 chairs and 5 tables. In terms of mathematical equations we can write this as, \[4x+5y\] . Divide by 4 in the equation \[12x+15y=58968\] , and solve them further.

Complete step-by-step answer:
Let us assume the cost of chair be x and cost of table be y.
According to the question, it is given that the cost of 12 chairs and 15 tables is Rs. 58,968.
In terms of mathematical equation we can write it as, \[12x+15y=58968\] ………………..(1)
We have to find the cost of 4 chairs and 5 tables.
In terms of mathematical equation we can write this as, \[4x+5y\] …………………(2)
We can see that L.H.S of equation (1) is four times of equation (2).
We can write equation (1) as,
\[\begin{align}
  & 12x+15y=58968 \\
 & \Rightarrow 3(4x+5y)=58968 \\
 & \Rightarrow 4x+5y=19656 \\
\end{align}\]
\[4x+5y=19656\] , L.H.S of this equation is the same as equation (2).
So, the cost of 4 chairs and 5 tables is Rs. 19656.
Hence, option (A) is the correct option.

Note: In this question, one can think to find the value of x and y which is not possible because we have only one equation and the number of variables is two. So, we cannot find the value of x and y. With the help of one equation, we can only find the value of another equation and it should be a multiple of the given equation.