Решение:

1. a) $$-3,5 - (-1,43) = -3,5 + 1,43 = -2,07$$
2. б) $$2,6 \times 4 \frac{3}{13} = 2,6 \times \frac{55}{13} = \frac{26}{10} \times \frac{55}{13} = \frac{2}{10} \times 55 = \frac{1}{5} \times 55 = 11$$
3. в) $$2 \frac{3}{4} : 1 \frac{5}{6} \times 10 = \frac{11}{4} : \frac{11}{6} \times 10 = \frac{11}{4} \times \frac{6}{11} \times 10 = \frac{6}{4} \times 10 = \frac{3}{2} \times 10 = 3 \times 5 = 15$$

Ответ:

• a) -2,07
• б) 11
• в) 15