1、1/5+1/3+2/15+7/12
=3/15+5/15+2/15+7/12
=10/15+7/12
=2/3+7/12
=8/12+7/12
=15/12 =5/4
2、19.59-32.48÷16+12×1.02
=19.59-2.03+12*(1+0.02)
=17.56+0.24+12
=17.8+12 =29.8
3、2/7*[(5/9+8/27)/(2/3)]
=2/7*3/2*(15/27+8/27)
=3/7*23/27
=23/63
1、1/5+1/3+2/15+7/12
=3/15+5/15+2/15+7/12
=10/15+7/12
=2/3+7/12
=8/12+7/12
=15/12 =5/4
2、19.59-32.48÷16+12×1.02
=19.59-2.03+12*(1+0.02)
=17.56+0.24+12
=17.8+12 =29.8
3、2/7*[(5/9+8/27)/(2/3)]
=2/7*3/2*(15/27+8/27)
=3/7*23/27
=23/63