7 audio cassettes and 3 videocassettes cost ₹1110, while 5 audio cassettes and 4 videocassettes cost ₹1350. Find the cost of audio cassettes and a video cassette.
7 audio cassettes and 3 videocassettes cost ₹1110, while 5 audio cassettes and 4 videocassettes cost ₹1350. Find the cost of audio cassettes and a video cassette.

Let’s assume the cost of an audio cassette and that of a video cassette be ₹a and ₹b, respectively. Then forming equations according to the question, we have

7a+3b=1110…(a)

5a+4b=1350… (b)

On multiplying equation (a)bb4 and equation (b)bb3,

We get,

28a+12b=4440…(c)

15a+4b=4050…(d)

Subtracting equation (iv) from equation (c),

28a-13a+12b-12b=4440-4050

13a=390

a=30

On substituting a=30 in equation (a)

7(30)+3b=1110

3b=1110-210

b=900/3

b=300

Therefore, it’s found that the cost of one audio cassette =₹30

And the cost of one video cassette =₹300