In 4 hours they will be 400 miles apart 4 times 55 is 220 and 4 time 45 is 180 since there going in opposer directions add the miles together and it equals 400 so it takes 4 hours
f(0) = ( f(k) +f(-k) ) / 2
f(0) = (16 - 4) / 2
f(0) = 12 / 2
f(0) = 6 → ANSWER
*Remember that f(0) = m(0) + n = n
If we have f(x) = mx + n, then:
f(k)= mk + n and f(-k)= -mk + n
If we add them:
f(k) + f(-k)
= mk + n -mk + n
= 2n
= 2f(0)
So we conclude that:
f(0) = [f(k) + f(-k)] / 2
60/100 / 60 are shaded out of the hundred. Simplified would be 3/5. The decimal would be 0.6.
This is only my opinion. I could be wrong.
My guess is:
Somebody else used that book before you, maybe last year or
the year before, and it was somebody who didn't mind writing
in his book.
One day he didn't have time to write down the homework in his
assignment notebook, so he just circled the homework problems
in his textbook.