Question

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:

Answer 1

chairs=x
table=y
from we get from the question
10x=4y
x=4/10y   .....................1
15x+2y=4000
then put the value of x from the equation 1st
15(4/10)y+2y=4000
then we get the value of y=500
and this value putt the equation 1st 
x=(4/10)500
x=200
then price of 12 chairs and 3 tables
12x+3y  ..............2nd
and the put the value of x and y in eqation2nd
and so the total value=3900