Ответы и объяснения

2014-03-02T11:32:40+04:00
1. 1/2-1/4+2/5=10/20-5/20+8/20=(10-5+8)/20=13/20 2. 3/4-1/2+7/8=24/32-16/32+28/32=(24-16+28)/32=36/32=1 4/32=1 1/8
2014-03-02T11:35:35+04:00
1/2-1/4+2/5=2/4-1/4+2/5=1/4+2/5=13/20
3/4-1/2+7/8=3/4-2/4+7/8=1/4+7/8=9/8=1 1/8