Выразим $$t$$:
$$t = 5\frac{25}{36} - (1\frac{1}{12} + 2\frac{3}{8})$$
$$t = 5\frac{25}{36} - \frac{83}{24} = \frac{205}{36} - \frac{83}{24} = \frac{205 \cdot 2}{36 \cdot 2} - \frac{83 \cdot 3}{24 \cdot 3} = \frac{410}{72} - \frac{249}{72} = \frac{161}{72} = 2\frac{17}{72}$$
Ответ: $$t = 2\frac{17}{72}$$