Solve using the addition property of equality. Don't forget to perform a check.
xminus9equals21
To solve x - 9 = 21 using the addition property of equality, we need to isolate x by adding 9 to both sides of the equation:
x - 9 + 9 = 21 + 9
x = 30
Now, we should perform a check by substituting x = 30 back into the original equation:
30 - 9 = 21
21 = 21
Since the result is true, we can confirm that x = 30 is the correct solution.