Answer:
Their is this website that has any basically every calculator on it and it show work. It is called "calculator soup"
The surface of the lake.
6
5
4
3
2
1
0 Here is the surface of the lake
-1
-2
-3
-4
-5 Here is the fish
-6
S=<span>−<span>1.546727
hope this helps.</span></span>
Answer: 3.5% with a 3.50 Tip
Reason: 25.00 - 21.50 = 3.50

Rounding to nearest thousand gives 76,000 mg of chlorine