30 * ( 1 5/6х+ 3 1/5) = 231
1 5/6х+3 1/5= 231:30
1 5/6х+ 3 1/5=7,7
1 5/6х= 7,7-3 1/5
1 5/6х=4,2
х= 4,2: 1 5/6
х=3,5
30 * ( 1 5/6х+ 3 1/5) = 231
1 5/6х+3 1/5= 231:30
1 5/6х+ 3 1/5=7,7
1 5/6х= 7,7-3 1/5
1 5/6х=4,2
х= 4,2: 1 5/6
х=3,5