Addition equations with 3 digit numbers 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 222 + 222 = 444. 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. 222 + x = 444). 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: 500 + x = 1200 500 + x - 500 = 1200 - 500 0 + x = 700 x = 700 Check the answer by substituting (700) for x in the original equation. The answer is correct if the expressions on each side of the equals sign have the same value. 500 + 700 = 1200 Return to Top

#### What number would complete the sentence?

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