第46页 - 通城学典课时作业本七年级数学苏科版江苏专用

解：原式$=5\frac 35+2\frac 25+(2\frac 78-1\frac 78)-(3\frac 5{12}+12\frac 7{12})$

$=8+1-16$

$=-7$

解：原式$=-12.5×0.8×0.1×317$

$=-10×0.1×317$

$=-317$

解：原式$=-1+(\frac 23-\frac 78+\frac {1}{12}-\frac {5}{6})×24$

$=-1+16-21+2-20$

$=-24$

解：原式$=(48+\frac {24}{25})×(-\frac {1}{48})$

$=-1-\frac {1}{50}$

$=-1\frac 1{50}$

解：原式$=7777×138 \frac {7}{9}-\frac {2}{9}×7777-38 \frac {5}{9}×7777$

$=7777×(138 \frac {7}{9}-\frac {2}{9}-38 \frac {5}{9})$

$=7777×100$

$=777700$

解：原式$=-\frac {4}{13}+\frac {3}{5}×(-\frac {5}{13})+\frac {5}{13}×\frac {8}{5}$

$=-\frac {4}{13}-\frac {3}{13}+\frac {8}{13}$

$=\frac {1}{13}$

解：因为$(\frac 13-\frac 56+\frac {5}{12}-\frac {2}{9}-2 \frac {1}{4})÷(-\frac {1}{36})$

$=(\frac {1}{3}-\frac {5}{6}+\frac {5}{12}-\frac {2}{9}-\frac {9}{4})×(-36)$

$=-12+30-15+8+81$

$=92$

所以原式$=\frac {1}{92} .$