Answer:
a=bc
Step-by-step explanation:
a/b=c
a=bc
let point A has coordinates (-9;12),B(-3;12),C(-5;10) and D(-11;10).Then the vector AB={6;0}, BC={2;-2}, CD={6;0}, AD={2;-2} and their and the length of the vectors
![|AB| = |CD| = \sqrt{ {6}^{2} + {0}^{2} } = \sqrt{36} = 6 \\ |BC| = |AD| = \sqrt{ {2}^{2} + {( - 2)}^{2} } = \sqrt{8}](https://tex.z-dn.net/?f=%20%7CAB%7C%20%3D%20%7CCD%7C%20%3D%20%5Csqrt%7B%20%7B6%7D%5E%7B2%7D%20%2B%20%7B0%7D%5E%7B2%7D%20%7D%20%3D%20%5Csqrt%7B36%7D%20%3D%206%20%5C%5C%20%7CBC%7C%20%3D%20%7CAD%7C%20%3D%20%5Csqrt%7B%20%7B2%7D%5E%7B2%7D%20%2B%20%7B%28%20-%202%29%7D%5E%7B2%7D%20%7D%20%3D%20%5Csqrt%7B8%7D%20)
![p = 6 + 6 + \sqrt{8} + \sqrt{8} = \\ = 12 + 2 \sqrt{8} = 17.66\approx18](https://tex.z-dn.net/?f=p%20%3D%206%20%2B%206%20%2B%20%5Csqrt%7B8%7D%20%2B%20%5Csqrt%7B8%7D%20%3D%20%5C%5C%20%3D%2012%20%2B%202%20%5Csqrt%7B8%7D%20%3D%2017.66%5Capprox18)
5 pairs
one kind of writing paper for each coloured envelope
the last three papers would have to be in envelope colours that were already use so they cant be counted.
Answer:
y = ![\frac{5}{4} x - 7](https://tex.z-dn.net/?f=%5Cfrac%7B5%7D%7B4%7D%20x%20-%207)
Step-by-step explanation:
Step 1: Add -5x to both sides.
5x − 4y + −5x = 28 + −5x
−4y = −5x + 28
Step 2: Divide both sides by -4.
![\frac{-4y}{-4} =\frac{-5x +28}{-4}](https://tex.z-dn.net/?f=%5Cfrac%7B-4y%7D%7B-4%7D%20%3D%5Cfrac%7B-5x%20%2B28%7D%7B-4%7D)
y = ![\frac{5}{4}x -7](https://tex.z-dn.net/?f=%5Cfrac%7B5%7D%7B4%7Dx%20-7)