怎样简便就怎样算4/5÷(1/5+3÷5)、(1/9-1/12)x4x9、2/3x8/9÷(2/5-4/15)、7/20÷[(5/6-2/3)x3]

Question

怎样简便就怎样算
4/5÷(1/5+3÷5)、(1/9-1/12)x4x9、2/3x8/9÷(2/5-4/15)、7/20÷[(5/6-2/3)x3]

Answer 1

4/5÷(1/5+3÷5)
=4/5÷(1/5+3/5)
=4/5÷4/5
=1
(1/9-1/12)x4x9
=(1/9-1/12)×36
=1/9×36-1/12×36
=4-3
=1
2/3x8/9÷(2/5-4/15)
=2/3×8/9÷2/15
=2/3×8/9×15/2
=2/3×15/2×8/9
=5×8/9
=40/9
7/20÷[(5/6-2/3)x3]
=7/20÷[5/6×3-2/3×3]
=7/20÷[5/2-2]
=7/20÷1/2
=7/20×2
=7/10