1. add 40 to the 40 and 25
2. now you have

3. then you have

4. then square root

5.then round answer to nearest tenth which is
well, the triangle is an isosceles, so it twin sides, and the twin sides make twin angles, as we see by the tickmarks on A and C, meaning AB = BC.
![\bf x+4=3x-8\implies 4=2x-8\implies 12=2x\implies \cfrac{12}{2}=x\implies 6=x \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ AC\implies x+4\implies 6+4\implies 10](https://tex.z-dn.net/?f=%5Cbf%20x%2B4%3D3x-8%5Cimplies%204%3D2x-8%5Cimplies%2012%3D2x%5Cimplies%20%5Ccfrac%7B12%7D%7B2%7D%3Dx%5Cimplies%206%3Dx%20%5C%5C%5C%5C%5B-0.35em%5D%20%5Crule%7B34em%7D%7B0.25pt%7D%5C%5C%5C%5C%20AC%5Cimplies%20x%2B4%5Cimplies%206%2B4%5Cimplies%2010)
A is your answer. Parallel lines never intersect. They both run the same direction, the same distance from each other.
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are parallel lines
the adjacent angles in a parallelogram