Answer:
uhh i think its 5 ignore this wishsbsns
a = 12
Step-by-step explanation:
Pythagorean Theorem: a^2 + b^2 = c^2
a^2 + 9^2 = 15^2 >> solve the exponent
a^2 + 81 = 225 >> subtract both sides by 81
a^2 = 144 >> square root
