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Multiplying the brackets:
#3(x-2)# is really 3 off # (x-2)#
That is #(x-2) + (x-2)+(x-2)#
So we end up with #x+x+x -2-2-2#
Which is 3 of #x# written as #3x# and we also have 3 lots of #-2# which is #-6#
So# 3(x-2) =3x-6#
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So the original equation of
#color(white)(xxxxxxx)color(brown)(-4=-8+3(x-2))#
Becomes
#color(white)(xxxxxxx)-4=-8 +3x-6#
#color(white)(xxxxxxx)-4=3x-14#
Add #color(blue)(14)# to both sides
#color(white)(xxxxxxx)color(brown)(-4) color(blue)(+14) color(brown)(=3x-14)color(blue)(+14)#
#color(white)(xxxxxxxxxxxxxx)10=3x#
Divide both sides by 3
#color(white)(xxxxxxxxxxxxxx)10/3 = 3/3 x#
#color(white)(xxxxxxxxxxxxxx)10/3 =x#
Write as per convention
#color(white)(xxxxxxxxxxxxxxxx)color(green)(x=10/3)#