Step-by-step explanation:
there is the rule
outside length × (outside length + inside length) is the same for all lines originating from the same point.
so, we have
CD(CD + x) = BC(BC + AB) = 6(6+20) = 6×26 = 156
8(8 + x) = 156
8 + x = 19.5
x = 11.5
