document.write( "Question 197240: 3r-7s=-28
\n" ); document.write( "7r+3s=70 \n" ); document.write( "
Algebra.Com's Answer #147877 by checkley77(12844)\"\" \"About 
You can put this solution on YOUR website!
3r-7s=-28 MULTIPLY BY 3
\n" ); document.write( "7r+3s=70 MULTIPLY BY 7 & ADD
\n" ); document.write( "9r-21s=-84
\n" ); document.write( "49r+21s=490
\n" ); document.write( "------------------
\n" ); document.write( "58r=406
\n" ); document.write( "r=406/58
\n" ); document.write( "r=7 ans.
\n" ); document.write( "3*7-7s=-28
\n" ); document.write( "21-7s=-28
\n" ); document.write( "-7s=-28-21
\n" ); document.write( "-7s=-49
\n" ); document.write( "s=-49/-7
\n" ); document.write( "s=7 ans.
\n" ); document.write( "Proof:
\n" ); document.write( "7*7+3*7=70
\n" ); document.write( "49+21=70
\n" ); document.write( "70=70 \n" ); document.write( "
\n" );