Assume that both portfolios A and B are well diversified, that E(rA) = 0.12, and E(rB) =0.08. If the economy has only one factor, and A = 1.61, whereas B = 0.72, what must be the risk-free rate?

Round your answer to 4 decimal places. For example if your answer is 3.205%, then please write down 0.0321.