b) A farmer sprays too much atrazine on his paddock resulting in a nearby lake becoming contaminated and killing sh present in the lake. EPA analysis...

Please explain each step to get the answer. Also, can you explain me the difference between these two equations and when to use them

1. [At]=[A]0e-kt
2. ln[A] = ln[A]0-kt

b) A farmer sprays too much atrazine on his paddock resultingin a nearby lake becoming contaminated and killing fish present in the lake. EPA analysis shows the atrazine concentration tobe 1.0 mg/L. Water quality guidelines stipulate a concentration below 0.15 mg/L atrazine to protect 80% of species. What timeshould authorities wait before re— introducing fish into the lake?