Jackson is playing a video game that has three castles to conquer within each level. Jackson has completed five levels so far if act represents the number of remaining levels to complete, which of the following equations can be used to find a total number of castles Jackson will have conquered once he completes the final level?
A. Y = 15x + 3
B. Y = 3x + 5
C. Y = 5x + 3
D. Y = 3x + 15
Since Jackson has completed five levels, he has conquered 5 levels * 3 castles per level = <<5*3=15>>15 castles.
Once he completes the final level, Jackson will also conquer an additional 3 castles.
Therefore, the correct equation is Y = 15x + 3.
The answer is option A.