Examine an equation, such as 15 -- x = 9. Fifteen and negative x are on one side of the equation and together those terms are said to equal the numerical value nine.
Move the integer from one side of the equation to the other. The goal is to get x by itself so that it ends up equal to the other side of the equation. To do this, use the opposite property applied to the integer, which in the case of 15 is positive and therefore added to the equation. Because both sides of the equation must remain equal or balanced, you must perform the same step to both sides of the equation.
Subtract 15 from both sides of the equation: +15 -- 15 -- x = 9 -- 15.
Simplify the equation. In the example, -x = -6. Even though it is not written, there is an understood "one" multiplied between the x and the negative sign: -x = (-1)(x). You need to remove the negative sign from the variable, however.
Divide both sides by the negative sign, (-1)(x). --x ÷ -1 = -6 ÷ -1. Simplify the equation, x = 6.
Read the following word problem. "A number plus the difference of that number and four equals twenty."
Write a formula to form an integer equation. Letting x represent the unknown number, you can form the equation x + (x -- 4) = 20.
Combine like terms and simplify: 2x -- 4 = 20. Add 4 to both sides of the equation and simplify. So 2x = 24. Divide both sides by 2 to isolate the variable and then simplify to x = 12.
Pug the value of "x" back into the formula by replacing every "x" variable with the integer value. 12 + (12 -- 4) = 20.
Solve the extended side of the equation to check for equality. Solve inside the parentheses first (12 -- 4 = 8), plug it back into the formula and finish solving the side. So 12 + 8 = 20. The equation is true.