15x - 3 = 9x + 1

15x -3 = 9x +1
15x -4 = 9x
24x - 4 = 0
24x=4
x= 4/24
x = 1/6

Guest's answer is incorrect......

15x - 3 = 9x + 1    add 3 to both sides

15x  = 9x + 4       subtract 9x from both sides

6x  = 4      divide both sides by 6

x  = 4/6  = 2/3