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.
You have to decide all sides to figure out all the kissing pieces
1.4 / 7
multiply by 10 in both up and down
(1.4*10) / (7*10)
14 / 70
divide by 7
(14/7) / (70/7)
2 / 10
divide by 2
(2/2) / (10/2)
1 / 5
37.5% of n is 81
0.375n=81
n=216
5/8 - 3/10
Find the common denominator:
Multiples of 8: 8, 16, 24, 32, 40 (8 x 5 = 40)
Multiples of 10: 10, 20, 30, 40 (10 x 4 = 40)
5/8 = 5*5 / 8*5 = 25/40
3/10 = 3*4 / 10 *4 = 12/40
Now you have 25/40 - 12/40
25 -12 = 13
Answer = 13/40
The answer is A.
