Money is required for an expansion. A company decides to borrow $18,363 from a bank at 13% interest; sell $27,111 in stocks at 8% interest; sell $48,311 in stocks at 17% interest; and $42,138 in reinvestment from last years profits which could have otherwise been drawing 4% interest.

The MARR for this expansion should exceed ________ %

The answer is 10.63% But I'm not sure how exactly, however I know I need to use a weighted average cost method.

I appreciate any help.