
Using Addition and SubtractionAfter studying this lesson, you will be able to:
A mathematical statement that contains an equal sign is called an equation . Steps for Solving Equations: 1. Remove parentheses by multiplying (this step is not always necessary) 2. Collect like terms on each side of the equal sign 3. Isolate the variable by undoing the operation 4. Check by substituting the solution into the original equation The equal sign divides equations into 2 parts or 2 sides. Equations are like balance scales. Whatever is done to one side, must be done to the other side in order to maintain equality or balance.
Example 1
Check: substitute 23 for x in the original equation (23) + 16 = 7 7 = 7 (always be sure the 2 sides are equal)
Example 2
Check: substitute 7 for a in the original equation (7) + (11) = 4 4 = 4 (always be sure the 2 sides are equal)
Example 3
Check: substitute 18 for y in the original equation 8 (18) = 10 (remember to add the opposite here) 10 = 10
Example 4
Check: substitute 18 for y in the original equation 5  (18) = 13 (remember to "add the opposite" here) 13 = 13
Example 5
Check: substitute 21 for x in the original equation (21) + 15 = 6 6 = 6
