400 times 7.50, step by step explanation

3000

Step-by-step explanation:

Just mulitiply 400 by 750 and you get 300000

then you put back the decimal place

3000.00

so it is 3000

The answer is 3 cm.

Circle A's diameter is 27, right? However, circle A is 3 times the value of the area of B. Because of that, you need to do 27/3, the inverse, in order to get the diameter of circle B. 

Next, because radius is half of the diameter, you do 9 divided by 3 or 9 times 1/2.