a. 12 . (x - 1) = 0
=> x - 1 = 0 : 12
=> x - 1 = 0
=> x = 0 + 1
=> x = 1.
b/ 70 - 5(x - 3) = 45
=> 5(x - 3) = 70 - 45
=> 5(x - 3) = 25
=> x - 3 = 25 :5
=> x - 3 = 5
=> x = 5 + 3
=> x = 8
X-1=12x0
X-1=0
X=0+1
x=1
b) 5x(X-3)=70-45
5x(X-3)=25
X-3=25:5
X-3=5
X=5+3
X=8