If the cost of 30 packets of 8 pencils each is ₹ 600, what is the cost of 25 packets having 12 pencils each?

Given, the cost of 30 packets of 8 pencils each is ₹600.

Now, the total number of pencils $= 30 \times 8 = \mathbf{240}$

By using a unitary method:

The price of 240 pencils = ₹600

→ The price of 1 pencil = $\frac{₹600}{240} = \mathbf{₹}\mathbf{ }\mathbf{2}\mathbf{.}\mathbf{5}$

Now, according to the question:

Total number of packets = 25

Number of pencils in each packet = 12

Thus,

 The total number of pencils = $25 \times 12 = \mathbf{300}$ 

By using a unitary method:

The cost of 1 pencil = ₹ 2.5

→ The cost of 300 pencils = $300 \times ₹2.5 = \mathbf{₹}\mathbf{750}$

Hence, the cost of 25 packets of 12 pencils each is ₹ 750.