-3*(-5 - 1 1/7x) - 1 = 5 - 3*(4 + 3/7x),
15 + 3*8/7х - 1 = 5 - 12 - 3*3/7х,
24/7х + 9/7х = 5 - 12 - 15 + 1,
33/7х = -21,
х = -21 : 33/7,
х = -21 * 7/33,
х = -49/11,
х = -4 5/11,
проверка:
-3*(-5 - 1 1/7*(-4 5/11) - 1 = 5 - 3*(4 + 3/7*(-4 5/11),
15 - 3*8/7*49/11 - 1 = 5 - 12 + 3*3/7*49/11,
15 - 168/11 - 1 = 5 - 12 + 63/11,
14 - 168/11 = -7 + 63/11,
154/11 - 168/11 = -77/11 + 63/11,
-14/11 = -14/11