Answer: is it -3,11
Step-by-step explanation:

Rounding to nearest thousand gives 76,000 mg of chlorine
5 is a coefficient. A coefficient is a number multiplied by a variable.
(2y+13) is a factor. It can be multiplied by 8 to get an extended answer.
-1 is a constant. A constant is a number that does not change.
Hope this helps!