98 11/80-5 13/48-90 13/15+21/50+6 11/15:1 2/3 *2=
1) 6 11/15: 1 2/3= 101/15:5/3= 101/15* 3/5=101/25=4 1/25
2)4 1/25*2=8 2/25
3) 98 11/80-5 13/48=93+(11/80-13/48)=93+(33/240-65/240)=93+ (-32/240)= 92+(240/240-32/240)=92 208/240
4) 92 208/240 - 90 13/15= 92 13/15-90 13/15=2
5)2+21/50= 2 21/50
6) 2 21/50+ 8 2/25=2 21/50+8 4/50=10 25/50= 10 1/2