Y = -9x - 10
The dolphin is diving 9 feet per second so the rate of change is -9.
It's also 10 feet below sea level which makes the y-intercept -10
Hope this helped!
For this case we must find an expression to find 40% of 25. So, we make a rule of three:
25 -----------> 100%
x -------------> 40%
Where "x" represents the amount that determines 40% of 25.

40% of 25 is 10. And an expression to find it is:

Answer:

51,000
5 in the ten thousands,
The thousands value is 1, the hundreds is 4 (less than 5 so we round down)
-2.77x - 11.4. Is the answer to your question