What does the "2" represent in 13^2/5

Point e(−5, 3) and point d(−4, −3) are located on the grid. which measurement is closest to the distance between point e and point d in units? a) 6.1 units b) 6.3 units c) 6.5 units d) 6.7 units

Awater holding tank measures 105 m long, 50 m wide, and 8 m deep. traces of mercury have been found in the tank, with a concen- tration of 60 mg/l. what is the total mass of mercury in the tank? answer in units of kg.

Extra points! find the missing dimension! need asap