The given expression is
[tex](8u^2+3u-4)+(8u^2+3u-1)-(3u^2-3u-8)[/tex]First, we use the distributive property
[tex]8u^2+3u-4+8u^2+3u-1-3u^2+3u+8[/tex]Second, we reduce like terms
[tex]\begin{gathered} 8u^2+8u^2-3u^2+3u+3u+3u-4-1+8 \\ 13u^2+9u+3 \end{gathered}[/tex]