Jacob invests $6,047 in a retirement account with a fixed annual interest rate of 8% compounded continuously. What will the account balance be after 15 years? A) $20,076.75
B) $17,280.22
C) $18,533.17
D) $21,640.41

Me because some of question i don’t understand

If x is 6, then 7x= a. 13 b. 42 c. 42x d. 76

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.