Пошаговое объяснение:

1)

[tex]2 \frac{3}{4} - 1 \frac{1}{2} = \frac{11}{4} - \frac{3}{2} = \frac{11}{4} - \frac{6}{4} = \frac{5}{4} [/tex]

2)

[tex] \frac{5}{4} - 3 \frac{5}{6} = \frac{5}{4} - \frac{23}{6} = \frac{30}{24} - \frac{92}{24} = - \frac{58}{24} = - 2 \frac{7}{12} [/tex]