An equation is a mathematical statement such that the expression on the left
side of the equals sign (=) has the same value as the expression on the right side.
An example of an equation is 200 + (- 600) = - 400.
One of the terms in an equation may not be know and needs to be determined. Often
this unknown term is represented by a letter such as x. (e.g. 200 + x = - 400).
The solution of an equation is finding the value of the unknown x. To find the
value of x we can use the subtraction property of equations which says: The two sides of an
equation remain equal if the same number is subtracted from each side. We may also use
the addition property of equations which says: The two sides of an equation remain equal
if the same number is added to each side.
- 500 + x = 400
- 500 + x + 500 = 400 + 500
0 + x = 900
x = 900
Check the answer by substituting the answer (900) back into the equation.
- 500 + 900 = 400