I'd suggest you enclose -1 and 5 within brackets as shown:
4( 2[-1] - [5] ). Do the work within parentheses FIRST: 4( -7 ).
Then multiply as indicated: -28
Answer:

Step-by-step explanation:
The standard form of this equation is

m stands for the gradient or the slope, and c represents the y-intercept

By definition we have that the average rate of change is given by:
AVR = (f (x2) - f (x1)) / (x2 - x1)
Substituting the values we have:
AVR = (204 - (-6)) / (10 - 0)
Rewriting we have:
AVR = (204 + 6) / (10 - 0)
AVR = 210/10
AVR = 21
Answer:
the average rate of change for f (x) from x = 0 to x = 10 is:
AVR = 21