Sure! To find the depletion expense for the current year, we need to calculate the depletion cost per ton of mineral deposits and then multiply it by the number of tons mined and sold.

Depletion is the process of allocating the cost of natural resources over the period when they are consumed or extracted. In this case, the mineral deposits are the natural resource being mined.

To calculate the depletion cost per ton, we divide the total cost of acquiring the mineral rights by the estimated number of tons of mineral deposits.

Depletion cost per ton = Total cost of acquiring mineral rights / Estimated number of tons of mineral deposits

In this case, the total cost of acquiring mineral rights is $67,500,000 and the estimated number of tons of mineral deposits is 30,000,000.

Depletion cost per ton = $67,500,000 / 30,000,000 = $2.25 per ton

Now, to find the depletion expense for the current year, we multiply the depletion cost per ton by the number of tons mined and sold.

Depletion expense = Depletion cost per ton * Number of tons mined and sold

In this case, the number of tons mined and sold is 4,000,000.

Depletion expense = $2.25 per ton * 4,000,000 tons = $9,000,000

Therefore, the depletion expense for the current year is $9,000,000.

Note: The above calculation assumes a straight-line method of depletion. Different methods of depletion, such as units-of-production or accelerated methods, may be used depending on the specific circumstances of the mining operation. It is always recommended to consult with a professional accountant or financial advisor for accurate and specific calculations in real-life scenarios.