solving for x in following proportion  TOPIC_SOLVED

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solving for x in following proportion

Postby losdawg25 on Thu Feb 05, 2009 2:31 pm

i am a beginner in algebra. i need to solve this. x+15 divided by 5 = x+3 divided by 3
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Postby stapel_eliz on Thu Feb 05, 2009 3:31 pm

losdawg25 wrote:i am a beginner in algebra. i need to solve this. x+15 divided by 5 = x+3 divided by 3

A basic property of proportions is that, if you "cross-multiply", you'll get the same value on either side. For instance:

. . . . .

...can be "proved" by showing that 1(6) equals 3(2). Using this "cross-multiplication" fact to solve looks like this example:

. . . . .

. . . . .

. . . . .

. . . . .

In your case, you have:

. . . . .

...which "cross-multiplies" as:

. . . . .

Multiply things out, and solve the resulting linear equation for the value of "x". :D

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