(12分之1+2分之1-12分之7)除以7分之1 25乘5分之3+2.75除以1又3分之2+60%

1,﹙1/12+1/2-7/12﹚÷1/7
=﹙1/12+6/12-7/12﹚÷1/7
=0÷1/7
=0
2, 25×3/5+2.75÷1又2/3+60％
=25×3/5+2.75×3/5+3/5
=﹙25+2.75+1﹚×3/5
=28.75×0.6
=17.25
3, 8×﹙3/8+1/27﹚+19/27
=8×3/8+8×1/27+19/27
=3+﹙8/27+19/27﹚
=3+1
=4