You use the lower case letter s for the sample standard deviation
You use the greek letter sigma (written as
) for the population standard deviation
The factors are
(m-6)(m+6)
Explanation:
Group the first two terms and factor out the common factor:
i.e m(m-6)
Repeat the procedure for terms 3 and 4.
6(m-6)
Regrouping:
m(m-6)+6(m-6)
On factoring out (m-6), we get:
(m-6)(m+6)
I hour = $8
h hours = $8h
Answer: p = $8h