1/2+7/8=4/8+7/8=11/8=1 3/8
5/9+11/36=20/36+11/36=31/36
8/9-5/7=56/63-45/63=11/63
1/4+3/7=7/28+12/28=19/28
13/20-4/15=39/60-16/60=23/60
14/15-11/12=56/60-55/30=1/60
19/20=38/40 и 7/8=35/40, 38/40>35/40
11/12=55/60 и 9/10=54/60, 55/60>54/60
04=4/10=2/5=14/35 и 3/7=15/35, 14/35<15/35<br>х+3/8=7/12
х=7/12-3/8=14/24-9/24=5/24
х-3/40=7/15
х=7/15+3/40=21/120+9/120=30/120=1/4