Question

During a certain month, a firm posted x letters with Rs. 5 stamps on each and another y letters with Rs. 3.50 stamps on each. Obtain an expression to find the total money Rs. M, spent on postage.
(A) \[M=Rs.\left( 5x+3.50y \right)\]
(B) \[M=Rs.\left( 5x-3.50y \right)\]
(C) \[M=Rs.\left( x+3.50y \right)\]
(D) \[M=Rs.\left( x-3.50y \right)\]

Answer 1

Hint: The amount for each stamp of the x letters and y letters is Rs. 5 and Rs. 3.50. Using the unitary method, calculate the money spent on x letter and y letter. At last, calculate the total price spent on postage.

Complete step by step answer:
According to the question, we are given that during a certain month, a firm posted x letters with Rs. 5 stamps on each and another y letters with Rs. 3.50 stamps on each.
The amount for each stamps of the letter = Rs. 5 ……………………………………………..(1)
The number of letters = \[x\] …………………………………………………….(2)
Using unitary method and from equation (1) and equation (2), we get
The total amount of x letters with Rs. 5 stamps = Rs. \[5x\] ……………………………………….(3)
The amount for each stamps of the letter = Rs. 3.50 ……………………………………………..(4)
The number of letters = \[y\] …………………………………………………….(5)
Using unitary method and from equation (4) and equation (5), we get
The total amount of x letters with Rs. 3.50 stamps = Rs. \[3.50y\] ……………………………………….(6)
On adding equation (3) and equation (6), we get
The total amount on postage = Rs. \[\left( 5x+3.50y \right)\] ………………………………………….(7)
In the question, we are given that an amount of Rs. M is spent on postage ……………………………….(8)
Now, from equation (7) and equation (8), we get
M = Rs. \[\left( 5x+3.50y \right)\] ………………………………………….(9)

So, the correct answer is “Option A”.

Note: In this question, one thing we have to take into consideration is unitary method. For instance, if the cost of one article is Rs. \[a\] then, the cost of b number of articles is Rs. \[ab\] . We know that total money would be the sum of x and y. So, we can eliminate options B and D since they represent the difference between x and y.