1) 5t+11 = 7t + 31, 2t = -20, t = -10.
2) 8t+3 = 3(5t-6), 8t+3 = 15t - 18, 7t = 21, t = 3.
3) 10t+18 = 2(5t+1), 10t+18 = 10t + 2 нет решений.
4)0,25t - 31 - 5 = t/4 - 18, -36=-18 нет решений
5) 13t-7+8 = 12t+11, t = 10,
6) 1,5t-37 - (1,5t-73) = 36, 36 = 36 - тождество. Ответ: при любом t.