If the equation \( a(b - c)x^2 + b(c - a)x + c(a - b) = 0 \) has equal roots, where \( a + c = 15 \) and \( b = \frac{36}{5} \), then \( a^2 + c^2 \) is equal to .
Find the missing code:L1#1O2~2, J2#2Q3~3, _______, F4#4U5~5, D5#5W6~6