What is the answer??

HK = 20

Step-by-step explanation:

LM = (1/2) HK          {Mid point theorem}

2*(10x - 90) = 10x - 80

2*10x - 2*90 = 10x - 80

20x - 180     = 10x - 80                   {add 180 to both sides}

           20x  = 10x - 80 + 180

          20x  = 10x +100              {Subtract 10x from both sides from }

     20x -10x = 100

            10x  = 100

                x = 100/10

               x = 10

HK = 10x - 80

     = 10*10 - 80

     = 100 - 80

     = 20

i think it is 18

step-by-step explanation: