What inference can be made about nelda's relationship with tracy?

Mount saint helen the great lakes and death valley are physical features of the earth which scientific term describes these features

Case # 51173878 weighs 814 pounds; case # 51173981 weighs 803 pounds; case # 51174058 weighs 817 pounds; case 51174178 weighs 815 pounds; case # 51174248 weighs 817 pounds; case # 51174495 weighs 781 pounds; case # 51174577 weighs 828 pounds. what are the case #'s of the two cases that weigh the same amount?

Blank is the amount of energy in a sound wave per unit of time and is also related to the loudness of a sound