\(\frac{7}{12}-\frac{2}{7}+\frac{1}{12}\)
\(=\left(\frac{7}{12}+\frac{1}{12}\right)-\frac{2}{7}\)
\(=\frac{8}{12}-\frac{2}{7}\)
\(=\frac{2}{3}-\frac{2}{7}\)
\(=\frac{14}{21}-\frac{6}{21}\)
\(=\frac{8}{21}\)
\(83,45-30,98-42,27\)
\(=83,45-\left(30,98+42,27\right)\)
\(=83,45-73,25\)
\(=10,2\)
Chúc bạn học tốt !!!