Answer: C. 150 km²
<u>Step-by-step explanation:</u>
Use similar triangle proportion to find x:

When you add and subtract be sure that the two fractions have the same denomination, and then add/subtract the numerators. I always do cross multiplication of the two fractions to obtain the same denominators-although there are various ways to do this.
Multiplying fractions is simply straight across.
Dividing fractions:
Keep, change, flip.
Keep the first fraction the same, change the sign to its opposite (ex:division flips to multiplication), and flip the numerator and the denominator of the second fraction. Then, preform the arithmetic from your "new" problem.
Answer:
Step-by-step explanation:
the first method :
s(x) = 2 - x and f(x) = 3x
(s f) (-7) = s(-7) ×f(-7)
but : s(-7) = 2 - (-7) =2+7 = 9
f(-7) = 3(-7) = - 21
so : (s f) (-7) = (9)×(-21) = - 189
the second method :
calculate : (s f) (x) == s(x)×f(x) = (2-x) 3x = 6x - 3x²
(s f) (-7) = 6(-7) -3 (-7)² = - 42 -147 = -189
Answer:

Step-by-step explanation:
we know that
The formula to find the sum is equal to

where
a1 is the first term
an is the last term
n is the number of terms
In this problem we have



substitute the values in the formula

The aswer would be B because you have to divide a couple numbers to get 20in.