5/6х+х= 3 2/3
5/6х+х=2
5х+6х=12
11х=12
х=12/11 и х= 1 1/11
13 >720
900>9
4 ч 35 м> 10800 с
28 м 57 с < 1800 с
15,17 25,37,35,37,45,47,55,57,65,67,75 ,77,85,87,95,97,105,107 ,115,117,125,127,135,137,145,147,155,157
56 × 4 : 7 = 8× 4 = 32 ( т ) - в клетку