Consider a simple firm that has the following market-value balance sheet:

Assets		Liabilities end equity
$1 010		Debt	$450
		Equity	560

Next year, there are two possible values for its assets, each equally likely: $1 200 and $970. Its debt will be due with 5.1% interest. Because all of the cash flows from the assets must go to either the debt or the equity, if you hold a portfolio of the debt and equity in the same proportions as the firm's capital structure, your portfolio should earn exactly the expected return on the firm's assets. Show that a portfolio invested 45% in the firm's debt and 55% in its equity will have the same expected return as the assets of the firm. That is, show that the firm's pre-tax WACC is the same as the expected return on its assets.

For a portfolio of 45% debt and 55% equity, the expected return on the debt will be ____% ??