6,98т=6980кг
5,9т=5900кг
5900-(55,2*100)=380кг
6980-5900-380=700кг
2/7х + 3/7х = 2 1/2
5/7х = 5/2
х = 5/2 : 5/7
х = 5/2 • 7/5 = 7/2 = 3.5
7,5х-2,46х=202,86
5,04х=202,86
х=202,86:5,04
х=40,25
15 разных способов
у Васи 7 марок=>
123,124,125,126,127,134,135,136,137,145,146,147,156,157,167.