Answer:
down in rate = 680-540 = 140
% change = 140*100/680 = 20.58%
The question is a bit ambiguous: you may mean

or

Anyway, in both cases, the domain of a function involving a square root is found by imposing the content of the root to be greateer than or equal to zero. So, in the first case you have

In the second case, you have

Answer:
y = 5x - 3
Step-by-step explanation:
5 times the input indicates multiplication, and the 3 less indicates subtraction.