James company is a trading retail. Currently, the company has a total capital of Rp 50 billion. The company's current capital structure:

Debt Mr. A (7.5% interest) with a total of 17.5 billion

Debt Mr. B (interest 10%) with a total of 20 billion

Debt Mr. C (15% interest) in the amount of 12.5 billion

Based on the data above, calculate the company's WACC. If the loan interest is 12%, is the fund used as capital for the project efficient?