Production function involving profit maximisation ​Hi, I don't get how the answer of d is deduced in this question because I don't think I made any mistakes in my calculation and have also used all the information given. After knowing L is 800, I found out the did 200*Q which gives me 5656 and I worked out the profit to be negative but it is not -15000. What did I do wrong in my calculation?

Thanks
Max 

Then you have: Max 

Which gives you: 

So L = 100, and you have a loss of 15000