document.write( "Question 1010926: Please help me solve this using substitution and elimination { { { -8x+9y=69 3y-6x=33 } } } \n" ); document.write( "
Algebra.Com's Answer #626440 by addingup(3677)\"\" \"About 
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We have two equations:
\n" ); document.write( "-8x+9y = 69
\n" ); document.write( "and
\n" ); document.write( "3y-6x = 33
\n" ); document.write( "Rearrange the terms on this last equation:
\n" ); document.write( "-6x+3y = 33 Multiply both sides of this equation times 3:
\n" ); document.write( "-18x+9y = 99
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\n" ); document.write( "Now let's subtract this last equation from the first:
\n" ); document.write( "-8x+9y = 69
\n" ); document.write( "-
\n" ); document.write( "-18x+9y = 99 (Note: We have a - -: -8x - -18x = -8x + 18x)
\n" ); document.write( "--------------
\n" ); document.write( "10x = -30
\n" ); document.write( "x= -3
\n" ); document.write( "Now let's find the value of y:
\n" ); document.write( "-8(-3)+9y= 69
\n" ); document.write( "24+9y = 69
\n" ); document.write( "9y = 45
\n" ); document.write( "y = 5
\n" ); document.write( "Finally, we'll check to see if we have the right answer. The right answer must make the two equations true (where one side equals the other, that's why it's called an equation)
\n" ); document.write( "-8x+9y = 69; -8(-3)+9(5)= 69; 24+45 = 69; 69 = 69
\n" ); document.write( "and
\n" ); document.write( "3y-6x = 33 3(5)-6(-3)= 33; 15+18 = 33 Both equations are true, we have the correct answer. \r
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