# Seven audio cassettes and three video cassettes cost Rs.1110, while five audio cassettes and 4 video cassettes costs Rs.1350. Find the cost of audio cassettes and video cassettes.

Last updated date: 19th Mar 2023

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Answer

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Hint:- Form a set of linear equations by using the given data. Use elimination method to solve this system of two equations and two unknowns.

Given , 7 audio cassettes & 3 video cassettes together costs Rs.1110 and 5 audio cassettes and 4 video cassettes together costs Rs.1350. We need to find the cost of the audio cassette and the video cassette.

Let, the cost of one audio cassette and video cassette be A and B respectively.

Now, according to the question,

7A + 3B =1110 -(1)

5A + 4B = 1350 -(2)

For finding the cost of one cassette of each type , we need to solve equation (1) and (2).

We have two equations and two unknowns. To solve these equations , we are going to use elimination by multiplication method i.e. we will multiply both equations with constants such that coefficients of either A or B becomes equal.

Multiplying Equation (1) with 5 and Equation(2) with 7 , we get

35A + 15 B = 5550 -(3)

35A + 28B =9450 -(4)

Now, we have coefficients of A equal in both the equations. On subtracting equation (4) from equation(3), we can get the value of B.

Subtracting Equation (4) from Equation(3),

28B – 15B = 9450-5550

13B=3900

B=300

Substitution the value of B in equation (1), we get

7A + 3(300) =1110

7A +900 = 1110

7A =210

A=30

Hence, A = 30 and B=300 i.e. the cost of one audio cassette is Rs.30 and cost of one video cassette is Rs. 300.

Note:- In these types of questions, there can be different ways to solve. For solving a system of equations of unknown variables , there are two basic methods. Method 1 is Substitution method and Method 2 is Elimination by multiplication method.

Given , 7 audio cassettes & 3 video cassettes together costs Rs.1110 and 5 audio cassettes and 4 video cassettes together costs Rs.1350. We need to find the cost of the audio cassette and the video cassette.

Let, the cost of one audio cassette and video cassette be A and B respectively.

Now, according to the question,

7A + 3B =1110 -(1)

5A + 4B = 1350 -(2)

For finding the cost of one cassette of each type , we need to solve equation (1) and (2).

We have two equations and two unknowns. To solve these equations , we are going to use elimination by multiplication method i.e. we will multiply both equations with constants such that coefficients of either A or B becomes equal.

Multiplying Equation (1) with 5 and Equation(2) with 7 , we get

35A + 15 B = 5550 -(3)

35A + 28B =9450 -(4)

Now, we have coefficients of A equal in both the equations. On subtracting equation (4) from equation(3), we can get the value of B.

Subtracting Equation (4) from Equation(3),

28B – 15B = 9450-5550

13B=3900

B=300

Substitution the value of B in equation (1), we get

7A + 3(300) =1110

7A +900 = 1110

7A =210

A=30

Hence, A = 30 and B=300 i.e. the cost of one audio cassette is Rs.30 and cost of one video cassette is Rs. 300.

Note:- In these types of questions, there can be different ways to solve. For solving a system of equations of unknown variables , there are two basic methods. Method 1 is Substitution method and Method 2 is Elimination by multiplication method.

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