a) 3x + 4 = 25 -> 3x = 25 - 4 -> 3x = 21 -> x = 21/3 -> x = 7
b) 5x - 5 = 25 -> 5x = 25 - 5 -> 5x = 20 -> x = 20 / 5 -> x = 4
c) 3x - 90 = x + 48 -> 3x - x = 48 + 90 -> 2x = 138 -> x = 138/2 -> x = 69
d) x - 12 = 3x/4 -> -12 = 3x - 4x/4 -> -12 = -x/4 -> -48 = -x -> 48 = x
e) 3x - 40 = x/2 + 20 -> 3x-40=x/2+20 -> 3x-x/2=+20+40 -> 3x-x/2=60 -> 6x-x=120 -> 5x=120 -> x=120/5 -> x=24
f) x/2 + 10 + x/3 = x -> x/2 +10 + x/3 = x -> 3x/6 + 60/6 + 2x/6 = 6x/6 -> 3x + 60 + 2x = 6x -> 3x + 2x - 6x = - 60 -> -x = - 60 -> x = 60
g) 3x/5 - 15 = 9 -> 3x/5 - 15 = 9 -> 3x/5 = 15 + 9 -> 3x/5 = 24 -> 3x = 24 x 5 -> 3x = 120 -> x = 120 / 3 -> x = 40
h) x + 3x = 84 -> 4x = 84 -> x = 84 / 4 -> x = 21
i) 3x + x = 72 18 . 3 = 54 -> 4x = 72 -> x = 72/4 -> x = 18
j) 2x + 5 = 35 -> 2x = 35 - 5 -> 2x = 30 -> x = 30/2 -> x = 15
k) x= carros 5y + y = 78
y= motos 6y = 78
x + y = 78 y = 78/6
Carros-> 5y = x y = 13
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