(4 1/6 + 11 1/4) * 4/15 = 2/3х + 5 2/3,
(25/6 + 45/4) * 4/15 = 2/3х + 5 2/3,
(50/12 + 135/12) * 4/15 = 2/3х + 5 2/3,
185/12 * 4/15 = 2/3х + 5 2/3,
37/9 = 2/3х + 5 2/3,
2/3х = 37/9 - 5 2/3,
2/3х = 37/9 - 17/3,
2/3х = 37/9 - 51/9,
2/3х = -14/9,
х = -14/9 : 2/3,
х = -14/9 * 3/2,
х = - 7/3,
х = - 2 1/3