12километров 080 метров =12080метров
А)1800:2=900 2) 900:30=30 3) 30+18=48 4)48:6=8 5)70*7=490 6)140:2=70 7)490-70=420 8)420:60=7 9)7+815
Б) 16:4=4 2)60-4=56 3)56:8=7 4)7*40=280 5)80*8=640 6)20*5=100. 7)640-100=540 8)540:6=90 9)280-90=190
№1.
3 7/9 + 5 1/6 = 3 14/18 + 5 3/18 = 8 17/18
8 7/16 + 3 3/10 = 8 70/160 + 3 48/160 = 11 118/160= 11 59/80
6 8/12 + 9 7/18 = 6 24/36 + 9 14/36= 15 + 38/36 = 16 2/36= 16 1/18
9 3/16 + 4 7/12 + 3 5/24 = 9 9/48 + 4 28/48 + 3 10/48= 16 47/48
№2.
8 3/4 - х = 3 5/16
х= 8 3/4 - 3 5/16 = 8 12/16 - 3 5/16
х= 5 7/16
проверим:
8 3/4 - 5 7/16 = 3 5/16
8 12/16 - 5 7/16 = 3 5/16
3 5/16 = 3 5/16
(х- 9 3/7 ) + 5 8/21 = 6 5/14
х - 9 3/7 = 6 5/14 - 5 8/21
х - 9 3/7 = 6 15/42 - 5 16/42
х - 9 3/7 = 41/42
х=41/42 + 9 3/7 = 41/42 + 9 18/42
х= 10 17/42
проверим:
(10 17/42 - 9 3/7 ) + 5 8/21 = 6 5/14
10 17/42 - 9 18/42 + 5 16/42 = 6 5/14
15 33/42 - 9 18/42 = 6 5/14
6 15/42 = 6 5/14
6 5/14 = 6 5/14