1 ) 5 + 3x = 4x - 9
⇔ 3x - 4x = -9 - 5
⇔ -x = -14
⇔ x = 14
2 ) ( x - 1 ) - ( 2x - 1 ) = x + 4
⇔ x - 1 - 2x + 1 = x + 4
⇔ -x - x = 4
⇔ -2x = 4
⇔ x = -2
3 ) 2 ( x - 3 ) / 4 - 1/2 = 6+9 /3 - 2
⇔ 3(2x - 6) / 12 - 6/12 = 72/12 + 36/12 - 24/12
⇒ 6x-18-6 = 72+36-24
⇔ 6x = 108
⇔ x = 18
4 ) 5x - 3 /2 - 3 = 2 + 5x /4
⇒ 2(5x-3) - 12 = 8 + 5x
⇔10x-6-12 = 8 +5x
⇔10x-5x = 8+6+`12
⇔5x =26
⇔ x = 26/5