The designer spends $2121 and $3 each for hat and he can sell it for $13.50 each.
If there are x number of hats, it will cost him (2121 + 3x) and he can gain 13.50x
The break even is when the cost and sales are equal.
Equating both expressions :
[tex]\begin{gathered} 2121+3x=13.50x \\ 2121=13.50x-3x \\ 2121=10.50x \\ x=\frac{2121}{10.50}=202 \end{gathered}[/tex]The answer is 202 hats