The answer is x = 0
To find this we must first find the length of IJ, Since IK is equal to 13 and JK is equal to 6, we can subtract to find the value of IJ.
IJ = IK - JK
IJ = 13 - 6
IJ = 7
Now, we know the value of HJ in terms of x, as we do the value of HI. So, we can add HI to IJ, which we just found and set equal to HJ
HJ = HI + IJ
2x + 15 = x + 8 + 7 ----> Simplify
2x + 15 = x + 15 -----> Subtract 15
2x = x ----> Subtract x
x = 0