Answer:
28
Explanation:
Since this is a right triangle, we can use the pythagorean theorem
a^2 +b^2 = c^2 where a and b are the legs and c is the hypotenuse
a^2 + 45^2 = 53^2
a^2 +2025=2809
a^2 = 2809-2025
a^2 =784
Take the square root of each side
sqrt(a^2) = sqrt(784)
a =28