Answer
Please see the work below.
Work Step by Step
We know that
a. $Mg^{26}_{12}+H^{2}_{1}\rightarrow Na^{24}_{11}+He^{4}_{2}$
so the short form notations are $Mg^{26}_{12}(d,\alpha)Na^{24}_{11}$
b. $O^{16}_{8}+n^{1}_{0}\rightarrow N^{16}_{7}+P^{1}_{1}$
