If the product of a number and -8 is subtracted from the number, the result is 7 more than the number. find the number. use x for the number.
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You have said that  [  x - (-8x) = x + 7  ] .

Note that  [ - (-8x) ] = 8x

So the equation may be written as  [  x + 8x = x + 7  ] .

Add up the 'x's on the left side:            9x = x + 7

Subtract 'x' from each side:                  8x = 7

Divide each side by 8 :                        x = 7/8