Respuesta :

ABCD is an iscosceles trapezoid. By definition, the legs AB and CD are congruent

AB = CD
7y-4 = 8y-18
8y-18 = 7y-4
8y-7y = -4+18
y = 14

Answer: 14

Note: the information about BC (the expression 4y-6) is extra unneeded info