SOLUTION: What is the value of x? https://static.k12.com/nextgen_media/assets/1543530-IM2_141011_021105.jpg

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Question 1064497: What is the value of x?
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Answer by math_helper(2461) About Me  (Show Source):
You can put this solution on YOUR website!
The smaller (upper) triangle has sides that are proportional to the larger (outermost) triangle. Let's set up a proportion:
+%283x-20%29%2F%28%283x-20%29%2B56%29+=+%289%2F%289%2B72%29%29+
Noting that +9%2F%289%2B72%29+=+9%2F81+=+1%2F9+
Let's us simplify to:
++%283x-20%29+%2F+%283x%2B36%29+=+1%2F9+
++9%2A%283x-20%29+=+3x%2B36+
+++27x+-+180+=+3x%2B36+
++24x+=+216+
++x+=+216%2F24+=+highlight%289%29+
—
Check: (3(9)-20) / (3(9)-20+56) = 7/63 = 1/9 (= 9/81 = 9/(72+9), so its ok)