Given information:
- Raju earns Rs. 1440 if he works for 12 days.

To find:
- How much will Raju earn if he works for 30 days?

Solution:

To find out how much Raju will earn if he works for 30 days, we need to determine his daily earning and then multiply it by the number of days he works.

Step 1: Calculate Raju's daily earning:
To find Raju's daily earning, we can divide the total amount he earns in 12 days (Rs. 1440) by the number of days (12).

Daily earning = Total earning / Number of days
Daily earning = Rs. 1440 / 12
Daily earning = Rs. 120

Therefore, Raju's daily earning is Rs. 120.

Step 2: Calculate Raju's earning for 30 days:
To calculate Raju's earning for 30 days, we can multiply his daily earning (Rs. 120) by the number of days (30).

Earning for 30 days = Daily earning * Number of days
Earning for 30 days = Rs. 120 * 30
Earning for 30 days = Rs. 3600

Therefore, if Raju works for 30 days, he will earn Rs. 3600.

In summary, if Raju earns Rs. 1440 for working for 12 days, his daily earning is Rs. 120. Therefore, if he works for 30 days, he will earn Rs. 3600.