I need help on Tales mathemathics below on image

x=5

Step-by-step explanation:

i'm assuming the upper left expression is x-1 and that the 3 horizontal lines are parallel

the three horizontal lines seem to be parallel, so we have (x-1)/6 = 6/(x+4). cross multiply to get (x-1)(x+4) = 36, or x^2 +3x - 4 = 36. subtract 36 from both sides to get x^2 + 3x -40 = 0, factor or use the quadratic formula to get (x+8)(x-5)=0, so x=-8 or x=5, since we are looking for a length x can't equal -8, so x=5,