An equation is a mathematical statement that has an expression on the left side of the equals sign (=) with the same value as the expression on the right side. An example of an equation is 222222 + 222222 = 444444.

One of the terms in an equation may not be known and needs to be determined. The unknown term may be represented by a letter such as x (e.g. 222222 + x = 444444). The equation is solved by finding the value of the unknown x that makes the two sides of the equation have the same value.

Use the subtractive equation property to find the value of x in addition equations. The subtractive equation property states that the two sides of an equation remain equal if the same number is subtracted from each side.

Example:
500000 + x = 1200000
500000 + x - 500000 = 1200000 - 500000
0 + x = 700000
x = 700000
Check the answer by substituting (700000) for x in the original equation. The answer is correct if the expressions on each side of the equals sign have the same value.
500000 + 700000 = 1200000