Anissa has 10 different colored markers and she wants to use 4 colors to create the poster. Therefore, in order to see how many ways she can select the 4 colors, we must use the combination formula:
![\begin{gathered} (n!)/(r!(n!-r!))=^nC_r \\ \\ n!=\text{ 10} \\ r!=4 \\ \\ \frac{10!}{4!(10!\text{ -4!\rparen}}= \\ \frac{(10!)(9!)(8!)(7!)(6!)}{4!\text{ \lparen6!\rparen}}=\text{ we eliminate 6!}which\text{ is repeated in both numerator and denominator} \\ \\ ((10!)(9!)(8!)(7!))/((4!)(3!)(2!)(1!))= \\ \\ (5,040)/(24)= \\ \\ 210 \end{gathered}]()
Therefore, there are 210 possible ways she can select 4 colors for the poter.