What is $x$ is this equation $(3x)/8 = (x+7)/12$ ?

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Answer 1 · 2016-07-11T19:40:55

$x = 2$

Cross multiply ( $a/b = c/d$ is the same as $ad = bc$ ).

$(3x)/8 = (x+7)/12$

$3x(12) = 8(x+7)$

$36x = 8x + 56$

$28x = 56$

$x = 2$

Answer 2 · 2016-07-16T12:19:02

$x = 2$

A method which works for solving any equation which has fractions, is to multiply by the LCM of the denominators.

This allows us to cancel the denominators which makes solving the equation much easier.

$(3x)/8 = (x+7)/12 " LCM = 24"$

$(24 xx3x)/8 = (24 xx(x+7))/12$

$(cancel24^3 xx3x)/cancel8 = (cancel24^2 xx(x+7))/cancel12$

$9x = 2(x+7)$

$9x = 2x +14$

$7x = 14$

$x = 2$

What is xx is this equation (3x)/8 = (x+7)/12(3x)/8 = (x+7)/12 ?