The answer to your question $0.42(that's included the 40% profit) So we do 30 divided by 5 = 6 x 2 = 12 then you add the $30+12= 42. the 12 is the 40 % profit.
Then you do 42 divided by 120 = 0.35 that is how much he will sell is include his 40 % of profit.
Let say if the was not adding the profit he will sell one can just 0.25 cent the 10 cent is the profit.
I hope is easy to understand the step I write to explain.
