Question

One pencil costs Rs. 2 and one fountain pen costs Rs. 15. What is the cost of x pencils and y fountain pens?

Answer 1

Hint:In order to solve this question, we need to remember the concept of unitary method, which is a technique for solving a problem by first finding the value of a single unit and then multiplying it with n to get the value of n units. For example, if we have been given the value of 1 unit as x, then we can say that the value of n units will be given by $x\times n$.

Complete step-by-step answer:
In this question, we have the price of a pencil and a fountain pen, that is, a pencil costs Rs. 2 and the fountain pen costs Rs. 15. And we have been asked to find the cost of x pencils and y fountain pens. To solve this question, we should know the concept of unitary method, which is a technique for solving a problem by first finding the value of a single unit and then multiplying it with n to get the value of n units. So, to find the cost of x pencils, we will multiply the cost of 1 pencil by x and to find the cost of y fountain pens, we will multiply the cost of 1 pen by y. And after that we will get the desired answer. So, we can write as,
Cost of x pencils = $Rs.2\times x\Rightarrow Rs.2x$
Similarly, the cost of y fountain pens = $Rs.15\times y\Rightarrow Rs.15y$
Hence, we can write the cost of x pencils and y fountain pens together as, Rs. (2x + 15y).

Note: We can solve this question by adding the cost of pencils, that is, Rs. 2 for x times and the cost of fountain pen, that is, Rs. 15 for y times. Or we can also solve this question by using the formula, cost of n item = cost of 1 item $\times $ n ,where n is number of items.