In trapezoid EFGH, EF¯¯¯¯¯ and HG¯¯¯¯¯¯ are the bases. Point J is the midpoint of EH¯¯¯¯¯¯ and point K is the midpoint of FG¯¯¯¯¯ . EF=3x+2 , HG=7x−2 , and JK=15 .

What is the value of x?