## Elementary Algebra

$-2+23i$
We multiply each term of the first complex number with the second complex number and then simplify: $(2+3i)(5+4i)$ =$2(5+4i)+3i(5+4i)$ =$10+8i+15i+12i^{2}$ =$10+23i+12i^{2}$ =$10+23i+12(-1)$ [as $i^{2}=-1$] =$10-12+23i$ =$-2+23i$