1. 16/26+11/26-t=77/78

27/26-t=77/78

27/26-77/78=t

81/78-77/78=t

4/78=t

2/39=t

2. 39/84+54/84-t=83/84

93/84-83/84=t

10/84=t

5/42=t

3.t+50/54-42/54=41/54

t+8/54=41/54

t=33/54

t=11/18

Доброго времени суток.

Решение во вложении.