B) 2-3-+1--3- 21.33+16.33 7474 191 E) 6-1--3-1- 7411441 3) 89·87-872 Л) 87⋅205203​−84⋅205203​ 3553 O) 5-4- 178817

Решение:

B) $$2\frac{1}{7} \cdot 3\frac{3}{4} + 1\frac{6}{7} \cdot 3\frac{3}{4} = 3\frac{3}{4} \cdot (2\frac{1}{7} + 1\frac{6}{7}) = 3\frac{3}{4} \cdot (2 + 1 + \frac{1}{7} + \frac{6}{7}) = \frac{15}{4} \cdot (3 + \frac{7}{7}) = \frac{15}{4} \cdot (3+1) = \frac{15}{4} \cdot 4 = 15$$

Е) $$6\frac{4}{7} \cdot 1\frac{1}{41} - 3\frac{9}{14} \cdot 1\frac{1}{41} = 1\frac{1}{41} \cdot (6\frac{4}{7} - 3\frac{9}{14}) = \frac{42}{41} \cdot (6\frac{8}{14} - 3\frac{9}{14}) = \frac{42}{41} \cdot (5\frac{22}{14} - 3\frac{9}{14}) = \frac{42}{41} \cdot (2\frac{13}{14}) = \frac{42}{41} \cdot \frac{41}{14} = 3$$

З) $$89 \cdot 87 - 87^2 = 87 \cdot (89 - 87) = 87 \cdot 2 = 174$$

Л) $$87 \cdot \frac{203}{205} - 84 \cdot \frac{203}{205} = \frac{203}{205} \cdot (87 - 84) = \frac{203}{205} \cdot 3 = \frac{609}{205}$$

О) $$5\frac{3}{17} \cdot \frac{5}{8} - \frac{5}{8} \cdot 4\frac{3}{17} = \frac{5}{8} \cdot (5\frac{3}{17} - 4\frac{3}{17}) = \frac{5}{8} \cdot (5 - 4 + \frac{3}{17} - \frac{3}{17}) = \frac{5}{8} \cdot (1 + 0) = \frac{5}{8} \cdot 1 = \frac{5}{8}$$

Ответ: Смотри решение выше