`19 5/8 : 7/12 + (-15 1/4) : 7/12`
`= 157/8 xx 12/7 + (-61/4) xx 12/7`
`= [157/8 + (-61/4)] xx 12/7`
`= 35/8 xx 12/7`
`= 15/2`
______________________________________
`2/5 . 1/3 - 2 2/15 : 1/5 + 3/5 . 1/3`
`= 2/5 . 1/3 + 3/5 . 1.3 - 32/15 : 1/5`
`= (2/5 + 3/5) . 1/3 - 32/15 xx 5`
`= 1 . 1/3 - 32/15 xx5`
`= 1/3 - 32/3`
`= -31/3`
a/
=\(\dfrac{157}{8}.\dfrac{12}{7}-\dfrac{61}{4}.\dfrac{12}{7}=\left(\dfrac{157}{8}-\dfrac{61}{4}\right).\dfrac{12}{7}=\dfrac{35}{8}.\dfrac{12}{7}\)
\(=\dfrac{15}{2}\)
b/
\(=\left(\dfrac{2}{5}+\dfrac{3}{5}\right).\dfrac{1}{3}-\dfrac{32}{15}.5=1.\dfrac{1}{3}-\dfrac{32}{3}=\dfrac{1}{3}-\dfrac{32}{3}=-\dfrac{31}{3}\)
\(19\dfrac{5}{8}:\dfrac{7}{12}+\left(-15\dfrac{1}{4}\right):\dfrac{7}{12}=\dfrac{157}{8}:\dfrac{7}{12}+\left(-\dfrac{61}{4}\right):\dfrac{7}{12}=\left\{\dfrac{157}{8}+\left(-\dfrac{61}{4}\right)\right\}:\dfrac{7}{12}=\dfrac{15}{2}\)
\(\dfrac{2}{5}.\dfrac{1}{3}-2\dfrac{2}{15}:\dfrac{1}{5}+\dfrac{3}{5}.\dfrac{1}{3}=\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{32}{15}:\dfrac{1}{5}+\dfrac{3}{5}.\dfrac{1}{3}=\left(\dfrac{2}{5}+\dfrac{3}{5}\right).\dfrac{1}{3}-\dfrac{32}{15}:\dfrac{1}{5}=\dfrac{1}{3}-\dfrac{32}{15}:\dfrac{1}{5}=-\dfrac{31}{3}\)
`19 5/8 : 7/12 +(-15 1/4):7/12`
`=[19 5/8 + (-15 1/4) :7/12`
`=[157/8+ (-59/4)]:7/12`
`=[157/8+(-118/8)]xx12/7`
`=39/8 xx 12/7`
`=117/14`
`---------`
`2/5 .1/3 - 2 2/15 : 1/5 + 3/5 . 1/3`
`=2/5 .1/3 - 32/15 : 1/5 + 3/5 . 1/3`
`=2/5 .1/3 - 32/15 . 5 + 3/5 . 1/3`
`=2/5 .1/3 - 32/3 + 3/5 . 1/3`
`=(2/5+3/5). 1/3 -32/3`
`=1 . 1/3 -32/3`
`=1/3 - 32/3`
`=-31/3`
\(=\dfrac{157}{8}:\dfrac{7}{12}-\dfrac{61}{4}:\dfrac{7}{12}\)
\(=\left(\dfrac{157}{8}-\dfrac{61}{4}\right):\dfrac{7}{12}\)
\(=\dfrac{35}{8}:\dfrac{7}{12}\)
\(=\dfrac{15}{2}\)
\(\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{32}{15}:\dfrac{1}{5}+\dfrac{3}{5}.\dfrac{1}{3}\)
\(=\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{32}{15}.5+\dfrac{3}{5}.\dfrac{1}{3}\)
\(=\dfrac{1}{3}\left(\dfrac{2}{5}+\dfrac{3}{5}\right)-\dfrac{32}{3}\)
\(=\dfrac{1}{3}.1-\dfrac{32}{3}\)
\(=\dfrac{1}{3}-\dfrac{31}{3}\)
\(=\dfrac{-30}{3}=-10\)