Choice D is correct. Let T represent Hailey's total number of shirts. If 21% of Hailey's total number of shirts is 7, then the following equation can be written: 0.21·T=7

To solve for T, multiply both sides of the equation by 0.21. The value of T is 33.3. Because 21% represented an approximate portion of the total number of socks, the value found for T is not an exact amount. Therefore, the best answer for the Hailey's total number of shirts is 33.

The total number of shirts is 33.