Answer:
Laurel bond will decrease by 7.72%
Hardy bond will decrease by 15.8% 
Step-by-step explanation:
current bond price $1,000 
 interest rate 8% 
 Laurel bond matures in 5 years, 10 semiannual payments 
 Hardy bonds matures in 16 years, 32 semiannual payments 
 if market interest increases to 10% 
 
Laurel bond: 
 $1,000 / (1 + 5%)¹⁰ = $613.91 
 $40 x 7.7217 (annuity factor, 5%, 10 periods) = $308.87 
 market price = $922.78
 % change = -7.72% 
 
Hardy bond: 
 $1,000 / (1 + 5%)³² = $209.87
 $40 x 15.80268 (annuity factor, 5%, 32 periods) = $632.11
 market price = $841.98
 % change = -15.8%