document.write( "Question 122178: Ricardo is 4 years less than twice as old as his sister. The sum of their ages is 20. How old is Ricardo? \n" ); document.write( "

Algebra.Com's Answer #89681 by josmiceli(19441) $\"\"$ $\"About$

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r = Ricardo's age
\n" ); document.write( "s = sister's age
\n" ); document.write( " $\"r+=+2s+-+4\"$
\n" ); document.write( " $\"r+%2B+s+=+20\"$
\n" ); document.write( " $\"s+=+20+-+r\"$
\n" ); document.write( "Substitute this value of $\"s\"$ in 1st equation
\n" ); document.write( " $\"r+=+2s+-+4\"$
\n" ); document.write( " $\"r+=+2%2A%2820+-+r%29+-+4\"$
\n" ); document.write( " $\"r+=+40+-+2r+-+4\"$
\n" ); document.write( " $\"3r+=+36\"$
\n" ); document.write( " $\"r+=+12\"$ answer
\n" ); document.write( "check answer
\n" ); document.write( " $\"r+%2B+s+=+20\"$
\n" ); document.write( " $\"12+%2B+s+=+20\"$
\n" ); document.write( " $\"s+=+8\"$
\n" ); document.write( " $\"r+=+2s+-+4\"$
\n" ); document.write( " $\"12+=+2%2A8+-+4\"$
\n" ); document.write( " $\"12+=+16+-+4\"$
\n" ); document.write( " $\"12+=+12\"$
\n" ); document.write( "OK \n" ); document.write( "

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