Resposta:

a)x=10

b)x=25

c)x=10

d)x=3

e)x=66

f)x=13

g)x=4

h)x=2

i)x=45/4

j)x=10

Explicação passo-a-passo:

a)

[tex]7x + 3x = 100[/tex]

[tex]10x = 100[/tex]

[tex]x = \frac{100}{10} [/tex]

[tex]x = 10[/tex]

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b)

[tex]25 - 4x = - 3x[/tex]

[tex]25 = - 3x + 4x[/tex]

[tex]x = 25[/tex]

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c)

[tex]3x = 37 - 7[/tex]

[tex]3x = 30[/tex]

[tex]x = \frac{30}{3} [/tex]

[tex]x = 10[/tex]

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d)

[tex]12x - 11 = + 6x + 7[/tex]

[tex]12x - 6x = 7 + 11[/tex]

[tex]6x = 18[/tex]

[tex]x = \frac{18}{6} [/tex]

[tex]x = 3[/tex]

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e)

[tex] \frac{x}{11} = 6[/tex]

[tex]x = 6 \times 11[/tex]

[tex]x = 66[/tex]

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f)

[tex]3x = 39[/tex]

[tex]x = \frac{39}{3} [/tex]

[tex]x = 13[/tex]

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g)

[tex] \frac{6x}{2} = 12[/tex]

[tex]6x = 12 \times 2[/tex]

[tex]6x = 24[/tex]

[tex]x = \frac{24}{6} [/tex]

[tex]x = 4[/tex]

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h)

[tex]4 + 2x = 8[/tex]

[tex]2x = 8 - 4[/tex]

[tex]2x = 4[/tex]

[tex]x = \frac{4}{2} [/tex]

[tex]x = 2[/tex]

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i)

[tex]7x - 5 = 3x + 40[/tex]

[tex]7x - 3x = 40 + 5[/tex]

[tex]4x = 45[/tex]

[tex]x = \frac{45}{4} [/tex]

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j)

[tex] - 9x + 10 = x - 90[/tex]

[tex]90 + 10 = x + 9x[/tex]

[tex]100 = 10x[/tex]

[tex] \frac{100}{10} = x[/tex]

[tex]x = 10[/tex]

Espero ter ajudado!

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