(4/(2/7+2)- x)=(2x-1/4)*6

(4/(2/7+14/7)- x)=(2x-1/4)*6

(4/(16/7)- x)=(2x-1/4)*6

(4*7/16)- x=12x-1,5

1,75-x=12x-1,5

-13x=-3,25

x=-3,25/-13

x=0,25