The answer is 180 m-72 and then yeah
Answer:

Step-by-step explanation:
step 1
Find the area of the plate
The area of a circle is given by the formula

we have
---> the radius is half the diameter
substitute

step 2
Find the area of the square napkin folded (is a half of the area of the square napkin)
we know that
The diagonal of the square is the same that the diameter of the plate
Applying Pythagorean theorem

where
b is the length side of the square
we have

substitute

solve for b^2
-----> is the area of the square
Divide by 2

step 3
Find the area of the space on the plate that is NOT covered by the napkin
we know that
The area of the space on the plate that is NOT covered by the napkin, is equal to subtract the area of the square napkin folded (is a half of the area of the square napkin) from the area of the plate
so

simplify

Answer:
Step-by-step explanation:
The surface area of a sphere (which the earth is considered to be) = 4 pi r^2
pi = 3.14
r = 6340
Area = 4 * 3.14 * 6340 * 6340 = 504856736 square km.
You should either round this to 505,000,000 or express a value in scientific notation.
5.05 * 10^8
I can solve with 2 methods:
I. Because the discount is 15 % of 18 $ , the price will be (100-15=85) 85 % of 18 $
18*85/100= 15,3 $ ( the sale price)
II. The discount is 15 % of 18$
15*18/100= 2,7$ ( the discount)
then I decrease it from the regularly price
18$-2,7$=15,3 $ (the sale price)
Personally I believe the first is an easier method.
I hope you understand and you can apply this in every similary problem.