Вычислите используя законы сложения=1/5+8/25+7/25 ; 1/7+2/21+3/7; 3/49+5/7+4/49;...

Решите задачу:

$1). \\ \frac{1}{5} + \frac{8}{25} + \frac{7}{25} = \frac{5}{25} + \frac{15}{25} = \frac{20}{25} = \frac{4}{5} =0,8 \\ 2). \\ \frac{1}{7} + \frac{2}{21} + \frac{3}{7} = \frac{2}{21} + \frac{4}{7} = \frac{2}{21} + \frac{12}{21} = \frac{14}{21} = \frac{2}{3} \\ 3). \\ \frac{3}{49} + \frac{5}{7} + \frac{4}{49} = \frac{7}{49} + \frac{5}{7} = \frac{1}{7} + \frac{5}{7} = \frac{6}{7} \\$ $4). \\ \frac{7}{10} + \frac{2}{15} + \frac{11}{30} = \frac{21}{30} + \frac{4}{30} + \frac{11}{30} = \frac{25}{30} + \frac{11}{30} = \frac{36}{30} = \frac{6}{5} = 1\frac{1}{5} =1,2$