50 POINTS !!
PLEASE HELP !! ILL GIVE BRAINLIEST TO THE RIGHT ANSWERS.

Step-by-step explanation:
54^2 + a^2 = 90^2
2916 + a^2 = 8100
a^2 = 8100 - 2916
a^2 = 5184
take the square root of 5184
a = 72
you could have also guessed that its a 3 4 5 right triangle
all the sides are multiples of 3 4 or 5