1题:
[(5/12+12/5)-1/8×2/3]÷1/20
=(169/60-1/12)×20
=(169/60)×20-(1/12)×20
=169/3-5/3
=164/3
=54又2/3
2题:
(2×4/5)÷(2/3÷4/9)
=8/5÷(2/3×9/4)
=8/5÷3/2
=8/5×2/3
=16/15
=1又1/15
1题:
[(5/12+12/5)-1/8×2/3]÷1/20
=(169/60-1/12)×20
=(169/60)×20-(1/12)×20
=169/3-5/3
=164/3
=54又2/3
2题:
(2×4/5)÷(2/3÷4/9)
=8/5÷(2/3×9/4)
=8/5÷3/2
=8/5×2/3
=16/15
=1又1/15