19)
[tex]90 = 21x + 6\\-21x = 6 - 90\\-21x = -84\\x = 4[/tex]
20)
[tex]75 = 11x - 2\\-11x = -2 - 75\\-11x = -77\\x = 7[/tex]
21)
[tex]60 = 8x - 4\\-8x = -4 - 60\\-8x = -64\\x = 8[/tex]
22)
[tex]132 = x + 139\\-x = 139 - 132\\-x = 7\\x = -7[/tex]
23)
[tex]-1 + 14x = 12x + 17\\14x - 12x = 17 + 1\\2x = 18\\x = 9[/tex]
24)
[tex]23x - 5 = 21x + 5\\23x - 21x = 5 + 5\\2x = 10\\x = 5[/tex]
