a,64.6+81.4+17.6
=6(64+17)+81.4
=6.81+81.4
=81(6+4)
=81.10
=810
\(a:\)\(64.6+81.4+17.6\)
\(=\left(64+17\right).6+81.4\)
\(=81.6+81.4\)
\(=81.\left(6+4\right)\)
\(=81.10\)
\(=810\)
\(b:\)\(\frac{930}{15}+\frac{310}{5}+196\)
\(=\frac{310}{5}+\frac{310}{5}+196\)
\(=124+196\)
\(=320\)
\(c:\)\(\frac{572}{26}-\frac{156}{13}\)
\(=\frac{286}{13}-\frac{156}{13}\)
\(=\frac{130}{13}\)
\(=10\)