document.write( "Question 397612: my problem says 'Sarah bought a laptop for $1800. The total cost, including tax, came to $1890. What is the tax rate?' I know there is a certain formula to solve it, I'm just not sure what it is. \n" ); document.write( "

Algebra.Com's Answer #281799 by nerdybill(7384) $\"\"$ $\"About$

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Sarah bought a laptop for $1800. The total cost, including tax, came to $1890. What is the tax rate?
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\n" ); document.write( "Let x = tax rate
\n" ); document.write( "then
\n" ); document.write( "1800 + 1800x = 1890
\n" ); document.write( "1800(1 + x) = 1890
\n" ); document.write( "1 + x = 1890/1800
\n" ); document.write( "x = 1890/1800 - 1
\n" ); document.write( "x = 1.05 - 1
\n" ); document.write( "x = .05
\n" ); document.write( "or
\n" ); document.write( "x = 5%\r
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