2/7*（1除以3/4减0.75除以1)
=2/7*(4/3-3/4)
=2/7*(16-9)/12
=2/7*7/12
=1/6
(4/19*2.532+1.768*4/19)+4.3除以1又4/15
=4/19*4.3+4.3*15/19
=4.3*(4/19+15/19)
=4.3*
9又3/4减15除以19-2/19*2
=39/4-15/19-2/19*2
=39/4-1
=35/4
=8又4分之3
0.25*28+1/4+71除以4
=0.25*4*7+1/4+71/4
=7+72/4
=7+18
=25
(1/2+1/3-5/6)*1.2
=(1/2+1/3-5/6)*12÷10
=(1/2*12+1/3*12-5/6*12)÷10
=(6+4-10)÷10
=0