Question 482750
A shorthand way of doing proportion problems such as these is to cross multiply them ... that is to multiply the numerator on the left side times the denominator on the right side and then to multiply the numerator on the right side by the denominator on the left side.  After doing those two multiplications, set the two products equal and solve.
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For this problem:
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{{{27/18=9/x}}}
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Multiply {{{27*x}}} to get {{{27x}}} and then multiply {{{9*18}}} to get {{{162}}}. 
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Then set the two products equal as follows:
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{{{27x = 162}}}
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Solve by dividing both sides by 27:
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{{{x = 162/27}}} and when you do the division on the right side you have the answer of:
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{{{x = 6}}}
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Hope this helps you to understand the problem and how to solve for simple proportions.