1) 6/11×7/8-6/8×6/11=6/11(7/8-6/8)=6/11×1/8=3/44
2)(7/10+3/4)×5=7/10×5+3/4×5=7/2+15/4=14/4+15/4=29/4
3)(21+2/5)×5/7=21×5/7+2/5×5/7=15+2/7
4) 2/5×15×1/10=30/5x1/10=3/5
1) 6/11×7/8-6/8×6/11=6/11(7/8-6/8)=6/11×1/8=3/44
2)(7/10+3/4)×5=7/10×5+3/4×5=7/2+15/4=14/4+15/4=29/4
3)(21+2/5)×5/7=21×5/7+2/5×5/7=15+2/7
4) 2/5×15×1/10=30/5x1/10=3/5