18,7а - 3 + 2 8/7 - 13,7а = 0
5а - 21/7 + 16/7 = 0
5а - 5/7 = 0
5а = 5/7
а = 5/7 : 5
а = 5/7 * 1/5
а = 1/7
18,7а - 3 + 2 8/7 - 13,7а = 0
5а - 21/7 + 16/7 = 0
5а - 5/7 = 0
5а = 5/7
а = 5/7 : 5
а = 5/7 * 1/5
а = 1/7