Вычислить: (12*0,8-1,8)/(2 1/2+2 1/15-1/4).

Ответ:

\[\frac{12 \cdot 0,8 - 1,8}{2\frac{1^{\backslash 30}}{2} + 2\frac{1^{\backslash 4}}{15} - \frac{1^{\backslash 15}}{4}} =\]

\[= \frac{9,6 - 1,8}{2\frac{30}{60} + 2\frac{4}{60} - \frac{15}{60}} = \frac{7,8}{4\frac{19}{60}} =\]

\[= \frac{78}{10}\ :\frac{259}{60} = \frac{39}{5} \cdot \frac{60}{259} =\]

\[= \frac{39 \cdot 12}{259} = \frac{468}{259} = 1\frac{209}{259}.\]