Answer:
6*15 = 5(x+5)
90 = 5x + 25
65 = 5x
x = 13
Explanation:
I've gone ahead and labeled some points.
There is a formula that says PA*PB = PC*PD, this is what you use. If you would like me to show why this works I would be happy to.
So what we have is PA = 6, PB = 9+6 = 15, PC = 5 PD = 5+x so let;s writ ethe formula with these values
6*15 = 5(x+5)
90 = 5x + 25
65 = 5x
x = 13
EDIT: Here is the explanation for the formula
If you form triangles PCB and PAD you can find angle D and angle B are the same, because they are inscribed angles that intersect the same arc of the circle. Also angle P is the same on both triangles since they are the same angle, so this means both triangles are similar.
This means DA is similar to BC, AP is similar to CP and PD is similar to PB. Similar sides means if you can multiply one side by a number to get to its similar side, then you can multiply all sides by that value to get all sides of that similar triangle.
This also means if you divide one side by its similar side you get the scale value, so this means if you do it to two different sets of similar sides you get the same number
