I have seen you ask this question twice before, so I will give you the answer that HugoD gave you:
In mathematics, "of" is translated as a multiplication.
So, you have :

.
Yes
Step-by-step explanation:

Its just correct..
The average speed = (speed 1 + speed 2)/2
the average speed = (80/10 + 100/20)/2
the average speed = (8 + 5)/2
the average speed = 13/2
the average speed = 6.5 km/minute
Answer:
the area of a circle is always pi so 3.14159
Step-by-step explanation: