Hello!
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The answer to your question is 495 ways.
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n = 12
r = 4
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nCr = n1 / (n-r)! r1
12C4 = 12! / (12-4)! 4!
12C4 = 12x11x10x9x8! / 8! 4!
12C4 = 11880 / 24
12C4 = 495
:)
12 divided by 15 = 160<span />
Slope = 5/-2 = -2.5
<span>pass through the origin (0,0)
</span>so equation
y = -2.5x
All you have to do is the price multiplied by the amount of kg. BUT make sure that they are both in the same units, in this case they are both in kilograms. So you do 7.25x20=$145