Vector Algebra

Find the value of '\(b\)' such that the scalar product of the vector \(\hat{\imath}+\hat{\jmath}+\hat{k}\) with the unit vector parallel to the sum of the vectors \(2 \hat{\imath}+4 \hat{\jmath}-5 \hat{k}\) and \(b \hat{\imath}+2 \hat{\jmath}+3 \hat{k}\) is unity