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How Do You Solve an Equation Using Subtraction?

Solve a + 14 = 23 for a

Summary

  1. 'a' is a variable
  2. Subtract 14 from both sides to solve for 'a'
  3. The 14's cancel out on the left
  4. 23 minus 14 is equal to 9
  5. Plug 9 in for 'a', and evaluate the equation to check our answer
  6. 9 plus 14 is 23, so the two sides are equal
  7. So 'a = 9' is the correct answer!

Notes

    1. Subtraction is the opposite of addition
    1. If we don't subtract from both sides, both sides of the equation won't be equal anymore
    1. Subtraction is the opposite of addition
    1. By subtracting 14 from the left side, we are able to get 'a' by itself
    2. 'a' is a variable
    1. 23 minus 14 is equal to 9
    2. Now we know 'a' is equal to 9
    3. 'a' is a variable
    1. By subtracting 14 from the left side, we are able to get 'a' by itself
    2. And on the right, 23 minus 14 is equal to 9
    3. We used the subtraction property of equality to solve for 'a'!
    4. 'a' is a variable
    1. Plug 9 in for 'a' in our original equation
    2. Then evaluate the expression to see if our answer is correct
    1. Put a 9 everywhere you see an 'a'
    2. 'a' is a variable
    1. Evaluating the expression on the left hand side, we get:
    2. 9 + 14 = 23
    3. Which is equal to the right hand side, 23
    1. We plugged our answer into the equation, and the equation became a true statement
    2. If it had been a false statement, our answer would be incorrect