algebra
posted by carolina on .
how do you work this problem ????
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X+(9)=5

x + (9) = 5
x = 5 + 9
x = 4 
but why does X = 5 +9

If A = B, then that implies that:
A + a = B + a
for any number a.
So, if
X + (9) = 5
then choosing a = 9 we get:
X + (9) + 9 = 5 + 9
Since (9) + 9 = 0 we have
X = 5 + 9 
You need to get the unknown on one side of the equation and the knowns on the other side. To do that you subtract 9 from the left side, change the sign and add it to the right side.

i still don't get it

ii still don't get it

Let's try this.
X+(9)=5
Remember, you can do anything to an equation as long as you do it to both sides. We want to get X (the unknown) on one side and the numbers on the other with the = sign between.
So, remove the parentheses first to obtain (remember that a + sign in front of the parentheses leaves the sign of the numbers inside the parentheses unchangedconversely, a  sign in front of the parentheses changes all the signs inside the parentheses when the parentheses are removed).
X  9 = 5
Now add +0 to both sides.
X9+9 = 5+9
Now combine the numbers
9 and +9 add to zero on the left while 5 and +9 add to +4 on the right.
X = +4.
That is the way to move anything from one side to the other. If you wish to move a + number simply subtract that number from both sides; if you wish to move a  number simply add that number to both sides. An easier way is to move anything from one side to the other by moving it and changing the sign.
I hope this helps. 
yes thanx now i get it