Given:
The cost of the total T-shirts = $30
each t-shirt cost the same whole dollar amount.
So, we need to factor the number 30
[tex]\begin{gathered} 30=1\times30 \\ 30=2\times15 \\ 30=3\times10 \\ 30=5\times6 \end{gathered}[/tex]So, the possible number of T-shirts are:
[tex]1,2,3,5,6,10,15,30[/tex]