Answer:
It's the last option "24 + 49i + 15i^2"
Explanation:
To solve you must do FOIL, (First, Outer, Inner, Last). To do this, you must do:
8 × 3 = 24 , 8 × 5i = 40i , 3i × 3 = 9i , and
3i × 5i = 15i^2 .
Don't forget to combine like terms.
Altogether: 24 + 49i + 15i^2 .
Picture does better job at explaining FOIL⤴⤴⤴
Hope this helps :)