17. Let \( \vec{a}=4 \hat{i}+3 \hat{j} \) and \( \bar{b}-3 \hat{i}-4 \hat{j}+5 \hat{k} \). If \( \vec{c} \) is a vector such that \( c \cdot|a \times b|+25=0, \vec{c} \cdot(i+j+k)=4 \), and projection of \( \vec{c} \) on \( \vec{a} \) is 1 , then the projection of \( \vec{c} \) on \( \vec{b} \) equals