one third of a number is 12 less than the number itself
Mathematics · Middle School · Tue Nov 03 2020
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We have this unknown number, lets call it X, and ⅓ of this X is 12 less than the number X.
Lets write it as an equation.
⅓ x= x+12
Lets put X on one side and the numbers on the other side of the equation.
⅓x - x = 12
We know that X is equal to 3/3x so lets express it this way on our equation.
⅓x - 3/3x = 12
Since the denominator is the same, we can just substract the nominators.
(x-3x)/3 = 12
Lets multiply both sides with 3.
x-3x = 12 *3
x-3x = 36
-2x = 36
Lets divide both sides with -2
x= -(36/2)
x= -18