7 audio cassettes and 3 video cassettes cost Rs 1110, while 5 audio cassettes and 4 video cassettes cost Rs 1350. Find the cost of an audio cassette and a video cassette.
Let the cost of an audio cassette be ‘a’ and a video cassette be ‘b’.
Given, 7 audio cassettes and 3 video cassettes cost Rs 1110.
⇒ 7a + 3b = 1110 -------- (1)
Also, 5 audio cassettes and 4 video cassettes cost Rs 1350.
⇒ 5a + 4b = 1350 -------- (2)
Multiplying eq1 by 4 and eq2 by 3 and subtracting eq2 from eq1.
⇒ 28a + 12b – 15a – 12b = 4440 – 4050
⇒ 13a = 390
⇒ a = Rs. 30
Substituting value of a in eq1
⇒ 7 × 30 + 3b = 1110
⇒ 3b = 900
⇒ b = Rs. 300