Решите уровнения a) 5m+6m=231 б) 7x-3x=412

5m + 6m = 231
11m = 231
m = 231 : 11 
m= 21
5 * 21  + 6 *21 = 231
21 * (5+6) = 231
21 * 11 = 231
231=231

7x-3x=412
4x=412
x=412 :  4
x= 103
7 * 103  -  3*103 = 412
103 * (7 - 3) = 412
103 * 4=412
412=412