How much would each of the following affect a firm's cost of debt, rd(1-t); its cost of equity, rs; and its weighted average cost of capital, WACC? Indicate by a plus ( + ), a minus () or zero (0) if the factor would raise, lower or have an indeterminate effect on the item in question. Assume other things are held constant. PROBABLE IMPACT ON In May, the Federal Reserve is expected to tighten credit (raises rates) Firm uses more debt The firm's corporate tax rate is lowered