bài 1
a)5/24+5/7+3/9=109/72
b)25%-1/1/2+0,5x12/5
=25%-3/2+0,5x12/5
=25%x1/100-3/2+0,5x12/5
=1/4-3/2+0,5x12/5
=1/4-3/2+6/5
=-1/20
C)(1/2+1/3+2/5):(-22 1/5)
=(1/2+1/3+2/5):(-111/5)
=-(1/2+1/3+2/5):111/5
=-37/30:111/5
=-1/18
d)-5/7x2/11+-5/7x9/11+1 5/7
=-5/7x2/11+-5/7x9/11+12/7
=-10/77+-5/7x9/11+12/7
=-10/77-45/77+12/7
=1
câu 2
a/x+3/20=-1/4
x=-1/4-3/20
x=-2/5
b/