1)5/6+2/9=15+4/18=19/18
5/6-2/9=15-4/18=11/18
9-13/6=18-13/6=5/6
13/6-5/6=8/6=4/3
7/8-1/2=7-4/8=3/8
2-3/10=20-3/10=17/10
17/10-3/10=14/10=7/513/12+2/3=13+8/12=21/12=7/4
2)5/6x2/9=5/27
5/6:2/9=5/3x9/1=45/3
3:13/6=1x2/13=2/13
13/6:2/13=1/2x1/1=1/2
7/8:1/2=7/8x2/1=7/4
7/8x7/4=49/32
4)=10/5=2/1
=4/4=1
=7/3
=7/7=1
=11/6
=8/8=1
=34/17
=38/19
=26/13
=33/11=3/1=3
=100/10=10/1=10
200/20=10/1=10
