45 + 89.23568 = 67.09876543456 - ? First, let's add 134. 23568 = 67.09876543456 - ? Now let's be smart just for a second :) We gonna replace this sign ? by x (x means the number we're looking for) 134. 23568 = 67.09876543456 - x We are solving x, right ? So let's equal it. Now, we have -x = 67.09876543456 - 134.23568 You got it ? I hope so :) Now we subtract -x = 67.136915 Now we have the number but we can not NEVER left the x with a negative sign, never :) To eliminate the negative sign we must divide both sides by -1 -x/-1 = 67.136915/-1 x/ = -67. 136915 That's the answer :)
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