-2= 5/2t? what is the value of t?

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.

This is about circle theorems. someone asap : (

According to the general equation for conditional probability if p(anb)=3/7 and p(b)=7/8 what is p(a i b)