At one point, certain U.S. Treasury bonds were callable. Consider the prices in the following three Treasury issues as of May 15, 2017:

05/15/2020		6.45				108.68750		108.75000			.31250		3.360
05/15/2020		7.50				109.21875		109.28125			.09375		4.180
05/15/2020		8.15				114.28125		114.46875			.46875		3.070

The bond in the middle is callable in February 2018. What is the implied value of the call feature? Assume a par value of $1,000. (Hint: Is there a way to combine the two noncallable issues to create an issue that has the same coupon as the callable bond?) Show how to solve with financial calculator.