D) The mean age of them is 15.
Mark with crown please!
Answer:

area: 136 cm
perimeter: 48 cm
Step-by-step explanation:
For the first one just subtract

for the second one you just have to break it into smaller, more digestible pieces (work below)
<span>To find the answer we need to find the raduis
Circumference = 2πr
r=</span>

r=

= 104.08
The diameter is 2r, hence the diameter is 208.16
If the rate to cross is 6ft. per second, time can be found by dividing the raduis by 6
It would take 34.7 seconds