If a and b are vectors such that | a + b |= 29 and a (2 i +3 j +4 k )=(2 i +3 j +4 k ) b…

If \(\vec{a} \text { and } \vec{b}\) are vectors such that \(|\vec{a}+\vec{b}|=\sqrt{29}\) and \(\vec{a} \times(2 \hat{i}+3 \hat{j}+4 \hat{k})=(2 \hat{i}+3 \hat{j}+4 \hat{k}) \times \vec{b} .\) then a possible value of \((\vec{a}+\vec{b})(-7 \hat{i}+2 \hat{j}+3 \hat{k})\) is