4. Найдите значение выражения: a) 1-4,8|+15,2|; 6) |-5,21|-|-4,81; B) |-6,51:13,9]; г) |26,5|-|3,9|; д) |-3|-|-|; e) | -21: 11|.

a) $$|-4.8| + |5.2| = 4.8 + 5.2 = 10$$.

б) $$|-5.21| - |-4.8| = 5.21 - 4.8 = 0.41$$.

в) $$|-6.5| \div |3.9| = 6.5 \div 3.9 = \frac{65}{39} = \frac{5}{3} = 1\frac{2}{3}$$.

г) $$|26.5| - |3.9| = 26.5 - 3.9 = 22.6$$.

д) $$|-3\frac{1}{3}| - |-\frac{5}{6}| = |-\frac{10}{3}| - |-\frac{5}{6}| = \frac{10}{3} - \frac{5}{6} = \frac{20}{6} - \frac{5}{6} = \frac{15}{6} = \frac{5}{2} = 2.5$$.

е) $$|-2\frac{1}{12}| \div |1\frac{1}{24}| = |-\frac{25}{12}| \div |\frac{25}{24}| = \frac{25}{12} \div \frac{25}{24} = \frac{25}{12} \cdot \frac{24}{25} = \frac{24}{12} = 2$$.

Ответ: a) 10; б) 0.41; в) 1; г) 22.6; д) 2.5; е) 2.