To solve the problem above, you must apply the proccedure shown below:
1. You have that in the circle AB=19, BC=10, and CD=5.
2. Then, to calculate the value of "x", you must apply the Intersecting secant theorem, as below:
(BC)(AC)=(CD)(xC)
BC=10
AC=AB+BC
AC=19+10
AC=29
CD=29
xC=x+CD=(5+x)
3. Now, you must susbtitute the values shown above into the formula and then, you must clear "x", as below:
(10)(29)=(5)(x+5)
290=5x+25
290-25=5x
265=5x
x=265/5
4. Then, you have that the value of "x" is:
x=53
5. Therefore, as you can see, the answer is:
x=53