To combine like terms, we add or subtract the coefficients of the terms with the same variables.
The expression is: 27stu + 21stu + 7stu - 22stu - 33stu
Combining the like terms, we have:
(27 + 21 + 7 - 22 - 33)stu
Simplifying the coefficients, we get:
0stu
Therefore, the simplified expression is 0stu.