Assume there are no prospective investment projects (I) that will yield an expected rate of return (r) of 25 percent or more, but that there are $5 billion of investment opportunities with an expected rate of return between 20 and 25 percent, an additional $5 billion between 15 and 20 percent, and so on. If the real interest rate is 15 percent in this economy, the aggregate amount of investment will be?