Answer:
It depends on your career but the important types are counting, addition, subtraction, multiplication and division.
10C4 represent the Combinations of 10 objects taken 4 at a time.
The formula for nCr is:

In the given case, n=10 and r=4. Using these values we get:

This means we can make 210 combinations of 10 objects taken 4 at a time.
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Answers:</h3>
The first ordered pair is ( -4 , -3 )
The second ordered pair is ( 8, 3 )
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Explanation:
The first point is (x,-3) where x is unknown. It pairs up with y = -3 so we can use algebra to find x
x-2y = 2
x-2(-3) = 2 ... replace every y with -3; isolate x
x+6 = 2
x = 2-6
x = -4
The first point is (-4, -3)
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We'll do something similar for the other point. This time we know x but don't know y. Plug x = 8 into the equation and solve for y
x-2y = 2
8-2y = 2
-2y = 2-8
-2y = -6
y = -6/(-2)
y = 3
The second point is (8, 3)
The exact value of sin (-270) is determined using the calculator in degrees mode. The answer is equal to 1. If the radians mode is used, -270 is equal to -2 pi/3. Hence using the calculator, we can verify that the answer is still 1. The value of -270 matters.
Would it be 2.5??? I think it would but not completely sure