(7/12-3/7)-(4/7-7/12)
1个回答

7/12-3/7)-(4/7-7/12)=7/12+7/12-3/7-4/7=14/12-1=2/12=1/6

5/7+19/25*4+21/25*199=5/7+(1-6/25)x4+(1-4/25)x199

=5/7+4-24/25+199-4x(200-1)/25

=5/7+203-24/25-32+4/25

=171+5/7-4/5

=171+25/35-28/35

=171-3/35

=5982/35

43/73*67+69*26/73

=(43x67+69x26)/73

=(2881+1794)/73

=4675/73