3/10+2/3= 5/13
21/8-1/4=20/4
2/5*7/8=14/40
3/10+2/3=(9+20)/30=29/30 ;
2 1/8-1/4=2 (1-2)/8=1 ( 9-2)/8=1 7/8 ;
2/5*7/8=7/20 ... (после сокращения на 2)...
3/10+2/3= 5/13
21/8-1/4=20/4
2/5*7/8=14/40
3/10+2/3=(9+20)/30=29/30 ;
2 1/8-1/4=2 (1-2)/8=1 ( 9-2)/8=1 7/8 ;
2/5*7/8=7/20 ... (после сокращения на 2)...