Posted by mary on Friday, April 22, 2011 at 7:54pm.
I am not a big fan of the expression "cross multiply"
What you want to do here is multiply both sides, all terms by -20 (or 20 would work too)
FIRST THE WAY YOU TYPED IT (probably wrong)
-12(-20) x + 2(-20 ) = -x(-20)
240 x - 40 = 20 x
220 x = 40
x = 2/11
NOW WHAT I THINK YOU MEAN
(-12x+10)(-20)/5 = -x (-20/20)
48 x -40 = -x
49 x = 40
x = 40/49
PARENTHESES ARE IMPORTANT WHEN TYPING EQUATION ON A COMPUTER (because of order of operations)
(-12x+10)(-20)/5 = -x (-20/20)
I made a sign error here
48 x -40 = +x
47 x = 40
x = 40/47
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