Please find the answer for this question

Answer:
15
Step-by-step explanation:
use pythagorean theorem and fill in the blanks and solve for a^2
Answer:
A=15
Step-by-step explanation:
This is a 3, 4, 5 triangle, so the perimeter of the triangle is a+4x+5x. You know that the x's go from 4x--20 and 5x--25. X=5, and 5x3=15
Good luck! :)