(5х + 15) * 10,3 = 0
5х + 15 = 0 : 10,3
5х + 15 = 0
5х = - 15
х = - 3
---------------------------------
(6х - 30) * (- 10,3) = 0
6х - 30 = 0 : (- 10,3)
6х - 30 = 0
6х = 30
х = 5
-----------------------------------
(4х - 28) * (- 2,9) = 0
(4х - 28) = 0 : (- 2,9)
4х - 28 = 0
4х = 28
х = 7