Hi, please help me with the following question and provide me with detailed explanation:

A regional restaurant chain, Club Caf, is considering purchasing a smaller chain, Sally's Sandwiches, which is currently financed using 20% debt at a cost of 8%. Club Caf's analysts project that the merger will result in incremental free cash flows and interest tax savings of $2 million in Year 1, $4 million in Year 2, $5 million in Year 3, and $117 million in Year 4. (The Year 4 cash flow includes a horizon value of $107 million.) The acquisition would be made immediately, if it is to be undertaken. Sally's pre-merger beta is 2.0, and its post-merger tax rate would be 34%. The risk-free rate is 8%, and the market risk premium is 4%. What is the appropriate rate for use in discounting the free cash flows and the interest tax savings?