Given:
Diameter of the hole = 30 cm
To find:
The area of the hole.
Solution:
The radius of a circle is always half of the diameter. It is given that the diameter of the hole is 30 cm. So, the radius of the hole is:


Area of a circle is:

Putting
and
in the above formula, we get



Therefore, the area of the hold is 706.5 square cm.
A ratio comparing two quantities measures in different units . An equation stating that two ratios or rates are equivalent. Percent proportion . One ratio or function compares part of a quantity to the whole quantity.
Answer:
1/2
Step-by-step explanation:
Simple probability is a ratio of the number of ways the thing we want to happen can to the total possible outcomes.
(For example, we flip a coin and want heads, but it can land on heads or tails. Our probability of getting heads is 1/2, one way to get heads over the 2 possible outcomes)
So for this problem, there's 20 possible things that CAN happen (3 + 7 + 10) and 10 ways we get what we want (a green marble).
Our probability of getting a green marble is
, which simplifies to 
I would subtract the 2nd from the first one
so -4x - -2x = -2x
4y - 4y = 0
-20 - -2 = -18
-2x = -18
now I would divide that by -2 to get the value for x
so no we have x = 9
now you just have to substitute that into one of the equations and simplify to get y
-2 X 9 + 4y = -2
-18 + 4y = -2
4y =16
y = 4