Question

помогите решить!!!
Заранеее спасибо

Answer 1

$1)~~\frac{3}{14} + \frac{1}{21} -\big( \frac{3}{5} - \frac{5}{5} \big)= \frac{3}{14} + \frac{1}{21} -\big(-\frac{2}{5}\big) = \frac{3}{14} + \frac{1}{21} + \frac{2}{5} = \\ \\ = \frac{3\cdot15+1\cdot10+2\cdot42}{210} = \frac{45+10+84}{210} = \frac{139}{210} \\ \\ \\ 2)~~2(a-1)=3 \\ ~~~~~2a-2=3 \\ ~~~~~2a=3+2 \\ ~~~~~2a=5 \\ ~~~~~a=2,5$


$3)~~ \frac{5}{11} - \frac{3}{33} + \frac{7}{1} = \frac{5}{11} - \frac{1}{11} + \frac{7}{1} = \frac{5-1+7\cdot11}{11} = \frac{4+77}{11} = \frac{81}{11} =7 \frac{4}{11} \\ \\ \\ 4)~~7(b+1)-2=3 \\ ~~~~~7b+7=5 \\ ~~~~~7b=5-7 \\ ~~~~~7b=-2 \\ ~~~~~b=- \frac{2}{7}$