Suppose you buy a 30 year zero coupon bond with a face value of $1000 and a 6% annual interest rate, compounded semi-annually. 1 minute after you buy the bond, the interest rate on this bond rises to 7%, compounded semi-annually. What is the percent change in the bond price?

I know the answer but can you explain how to do it as well as how to enter to solve it on a finanical calculator (BA II Plus).

Thank you