Let's add parenthesis inside the expression to make it true
[tex]\begin{gathered} (15-(2\times3+4))\div2=2.5 \\ \end{gathered}[/tex]Let's solve the expression to check
[tex]\begin{gathered} (15-(2\times3+4))\div2 \\ (15-(6+4))\div2 \\ (15-10)\div2 \\ 5\div2 \\ 2.5 \end{gathered}[/tex]