Simplification question for IBPS, SBI, RBI, PO, UPSC, State-PSC, Railways, SSC

[Q] The price of 10 chairs is equal to that of 4 tables. The price of 15 chairs and 2 tables together is Rs. 4000. The total price of 12 chairs and 3 tables is:
(a) 5900
(b) 2900
(c) 3900
(d) 4900

Solution

Answer    (c)
Explanation
----
Let the cost of a chair and that of a table be Rs. x and Rs. y respectively.

Then, 10x = 4y   or   y =	5	x.
	2

15x + 2y = 4000

15x + 2 x	5	x = 4000
	2

20x = 4000
x = 200.

So, y =		5	x 200		= 500.
		2

Hence, the cost of 12 chairs and 3 tables = 12x + 3y
    = Rs. (2400 + 1500)
    = Rs. 3900.