document.write( "Question 1050807: Liza is 25 years younger than her mother. After 4 years, her mother's age will be twice as old as her. How old are they? \n" ); document.write( "

Algebra.Com's Answer #666429 by advanced_Learner(501) $\"\"$ $\"About$

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L=M-25\r
\n" ); document.write( "\n" ); document.write( "2(L+4)=M+4
\n" ); document.write( "2L+4=M\r
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\n" ); document.write( "\n" ); document.write( " $\"M-L=25\"$
\n" ); document.write( " $\"M-2L=4\"$ \r
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Solved by pluggable solver: SOLVE linear system by SUBSTITUTION

Solve:
\n" ); document.write( " $\"+system%28+%0D%0A++++1%5Cm+%2B+-1%5Cl+=+25%2C%0D%0A++++1%5Cm+%2B+-2%5Cl+=+4+%29%0D%0A++\"$ We'll use substitution. After moving -1*l to the right, we get:
\n" ); document.write( " $\"1%2Am+=+25+-+-1%2Al\"$ , or $\"m+=+25%2F1+-+-1%2Al%2F1\"$ . Substitute that
\n" ); document.write( " into another equation:
\n" ); document.write( " $\"1%2A%2825%2F1+-+-1%2Al%2F1%29+%2B+-2%5Cl+=+4\"$ and simplify: So, we know that l=21. Since $\"m+=+25%2F1+-+-1%2Al%2F1\"$ , m=46.
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\n" ); document.write( " Answer: $\"system%28+m=46%2C+l=21+%29\"$ .
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