B.6 would be the right answer because thats the ratebin which it drops
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2x+x-7+3x-20=87cm
6x-27=87
6x=114
x=19
Therefore the sides are:12cm, 38cm, and 37cm
Composition means that you can plug g(x) into f (x). This is written as "( f o g)(x)", which is pronounced as "f-compose-g of x". And "( f o g)(x)" means " f (g(x))". That is, you plug something in for x, then you plug that value into g, simplify, and then plug the result into f. hope this helps.
