the equation is

Clearing c, we have

So we just need to make the substitutions. The first one is e = 1.4, so we will have

For the second one, we have e=2.2

In the second one, we start with 124 lt of water and we add 9 lt per minute (I think, it doesn't say). So, in this case the equation is

where L is the number of liters of water and t is the time in minutes. First we are asked for the first 4 minutes, so we have

Then, after the first 80 minutes we have
