document.write( "Question 1094203: the sum of two numbers is -9 and their difference is 31, what are the numbers? \n" ); document.write( "
Algebra.Com's Answer #708796 by addingup(3677)\"\" \"About 
You can put this solution on YOUR website!
x+y = -9 (1)
\n" ); document.write( "x-y = 31 here, add y on both sides
\n" ); document.write( "x = 31+y using this value for x, substitute in (1)
\n" ); document.write( "31+y+y = -9
\n" ); document.write( "2y = -40
\n" ); document.write( "y = -20
\n" ); document.write( "and since x-y = 31:
\n" ); document.write( "x-(-20) = 31
\n" ); document.write( "x+20 = 31
\n" ); document.write( "x = 11
\n" ); document.write( "--------------------
\n" ); document.write( "Check:
\n" ); document.write( "x+y = -9
\n" ); document.write( "11+(-20) = -9 correct
\n" ); document.write( "x-y = 31
\n" ); document.write( "11-(-20) = 11+20 = 31 also correct
\n" ); document.write( " \n" ); document.write( "
\n" );