8 units
(This is how I get the answer)
Answer: C
Step-by-step explanation:
You can solve this by first multiplying both sides of the fraction by the conjugate of the denominator.
In this case, the conjugate is (8 - 2i).
So:

Simplify:

Simplify again, knowing that i^2 = -1

Then, divide both numbers in the numerator by 68 to get your answer.

Answer:
1/3
Step-by-step explanation:
How much part can sally paint in an hour ?
a ÷ 7 = a/7
And what about Steve ?
a ÷ 9 = a/9
Where, a is the total area of the room.
So, let the time taken by both of them to paint the room together be 't'
So,
t(a/7 + a/9) = a
t(9a/63 + 7a/63) = a
t(16a/63) = a
t = 63/16 ≈ 4 hr