Вариант 3 1. Найди значение выражения: a) 4,2 ; 25,2 б) 2 2- 5 1; 1 15 в) 1,56 1 2- 6

a) $$\frac{4.2}{25.2} = \frac{42}{252} = \frac{1}{6}$$

б) $$2 \frac{2}{5} \div 1 \frac{1}{15} = \frac{12}{5} \div \frac{16}{15} = \frac{12}{5} \times \frac{15}{16} = \frac{3 \times 3}{4} = \frac{9}{4} = 2 \frac{1}{4}$$

в) $$1.56 \div 2 \frac{1}{6} = 1.56 \div \frac{13}{6} = 1.56 \times \frac{6}{13} = \frac{156}{100} \times \frac{6}{13} = \frac{12 \times 6}{100} = \frac{72}{100} = 0.72$$

Ответ: a) $$\frac{1}{6}$$, б) $$2 \frac{1}{4}$$, в) $$0.72$$