To add these distances, they must share the same unit so first you need to first convert the swim distance from meters (m) to kilometers (km) before adding it to the bike and run distances which are already in km. To convert 400 meters to kilometers, divide the distance by 1000 to get 0.4km then add the remaining distances:

total distance = swim + bike + run
total distance = 0.4km + 40.5km + 14.8km
total distance = 55.7km

In order to find how many additional workers are needed to staff the extra crews you first need to calculate how many workers are on a crew. There are 6 workers at the company now and that's enough to staff 3 crews so there are \( \frac{6}{3} \) = 2 workers on a crew. 6 crews are needed for the busy season which, at 2 workers per crew, means that the roofing company will need 6 x 2 = 12 total workers to staff the crews during the busy season. The company already employs 6 workers so they need to add 12 - 6 = 6 new staff for the busy season.

Use PEMDAS (Parentheses, Exponents, Multipy/Divide, Add/Subtract):

5 + (3 + 2) ÷ 2 x 3 - 3²
P: 5 + (5) ÷ 2 x 3 - 3²
E: 5 + 5 ÷ 2 x 3 - 9
MD: 5 + \( \frac{5}{2} \) x 3 - 9
MD: 5 + \( \frac{15}{2} \) - 9
AS: \( \frac{10}{2} \) + \( \frac{15}{2} \) - 9
AS: \( \frac{25}{2} \) - 9
AS: \( \frac{25 - 18}{2} \)
\( \frac{7}{2} \)
3\(\frac{1}{2}\)

The hourly error rate for this machine is the error rate in parts per 100 multiplied by the number of parts produced per hour:

\( \frac{7}{100} \) x 7 = \( \frac{7 \times 7}{100} \) = \( \frac{49}{100} \) = 0.49 errors per hour

So, in an average hour, the machine will produce 7 - 0.49 = 6.51 error free parts.

The machine ran for 24 - 5 = 19 hours yesterday so you would expect that 19 x 6.51 = 123.7 error free parts were produced yesterday.

To multiply terms with exponents, the base of both exponents must be the same. In this case they are so multiply the coefficients and add the exponents:

-6a⁵ x 7a²
(-6 x 7)a^{(5 + 2)}
-42a⁷