Given that $1 is equal to Rs. 80, we can use this information to determine the cost of 3 eggs in rupees when a dozen eggs cost $2.

First, let’s calculate the cost of 1 egg in dollars. Since a dozen eggs cost $2, we divide $2 by 12 to find the cost of 1 egg:

Cost of 1 egg in dollars = $2 / 12 = $1/6

Next, we can convert the cost of 1 egg from dollars to rupees using the given conversion rate of $1 = Rs. 80:

Cost of 1 egg in rupees = Cost of 1 egg in dollars × Conversion rate = $1/6 × Rs. 80 = Rs. (80/6) = Rs. 40/3

Now, to find the cost of 3 eggs in rupees, we multiply the cost of 1 egg in rupees by 3:

Cost of 3 eggs in rupees = 3 × (Rs. 40/3) = Rs. (40/1) = Rs. 40

Therefore, 3 eggs would cost Rs. 40.

In summary, we used the given conversion rate of $1 = Rs. 80 to determine the cost of 1 egg in rupees. We then multiplied the cost of 1 egg by 3 to find the cost of 3 eggs, which turned out to be Rs. 40.