Answer:

Step-by-step explanation:
It's already in a form that only ha positive exponents. Just to state it though you could rewrite it as
or
The question asks for positive exponents though so yu don't need to do that.
You also need to know
so in this case 
so 
The area formula of a circle is
× π.
With that being said, we can solve both problems!
Starting with part A:
-The radius we know is 21cm. From there, we can substitute in our formula with the new value.
x π
From there, we can square our radius:
(21 x 21) x π
(441) x π
And finally, we can multiply by pi to get our answer.
(441) x π
1385.44236023
Which rounded to the nearest tenth is 1385.4. Therefore, the area of the porthole is 1385.4 centimetres.
The second part can be followed with the same process, hopefully you understand the concept enough to where you're comfortable solving problems like this on your own. Feel free to reach out if you have any further trouble!
<em>Hope this helped! :)</em>
Answer:
2x15-5=30-5=25 So, the answer is 25.
Please try 43 I'm not sure
Answer:
I would answer but I cannot see it sorry :D
Step-by-step explanation: