Computation of internal rate of return of the bond

A. You buy a bond at 940 with a coupon of 8%. 5 years later you sell it for 970. What was your internal rate of return?

B. You buy a 30 year zero coupon bond when interest rates were 7%. Three years later you sell it when interest rates were 8%. What was your internal rate of return?

C. You buy a bond at 900 with a current yield of 8%. 4 years later you sell it for 990. What was your internal rate of return?