(2/3) / (2/9+1/3х) + 1/2 = 13/14,
(2/3) / (2/9+1/3х) = 13/14 - 1/2,
(2/3) / (2/9+1/3х) = 13/14 - 7/14,
(2/3) / (2/9+1/3х) = 6/14,
2/9 + 1/3х = 2/3 : 6/14,
2/9 + 1/3х = 2/3 * 14/6,
2/9 + 1/3х = 14/9,
1/3х = 14/9 - 2/9,
1/3х = 12/9,
х = 12/9 : 1/3,
х = 12/9 * 3,
х = 12/3,
х = 4