18 chairs and 4 tables cost ₹7,100 and 18 chairs and 7 tables cost ₹7,700. What is the cost of 18 chairs and 5 tables?

Correct option is C

Given:

The cost of 18 chairs and 4 tables = ₹7,100

The cost of 18 chairs and 7 tables = ₹7,700

Solution:

Let the cost of one chair be C and the cost of one table be T

From the condition;

18C + 4T = 7100........(1)

18C + 7T = 7,700........(2)

Subtract equation 1 from equation 2:

we get , 3T = 600 

so, T = 200 

Substituting T = 200 into equation 1;

18C + 4(200) = 7,100

18C + 800 = 7,100

18C = 7,100 - 800 = 6,300

C  = $$\frac{6,300}{18}$$​ = 350

Now, cost of 18 chairs and 5 tables:

18C + 5T = 18(350) + 5(200) = 6,300 + 1,000 = 7,300

The cost of 18 chairs and 5 tables is ₹7,300