Answer: 21
In order to find the answer you have to multiply FJ and JH which is equal to 6x+24.
After, multiply GJ and JE which is equal to 90.
After doing all these steps equal your findings:
6x+24= 90
x= 11
The length of FH is asked so, you have found x, which is equal to 11
FH= 6+(11+4)= 21