To represent the situation with an inequality, we need to consider the total cost of ordering 9 shirts, where \( t \) is the cost of one shirt.
The total cost for 9 shirts can be expressed as:
\[ 9t \]
The student council wants to keep this total cost less than or equal to $171, leading us to the following inequality:
\[ 9t \leq 171 \]
This inequality represents the situation where the cost of 9 shirts should not exceed $171.