What value should come in place of the question mark ($?$) in the following equation? $(\frac{13.31}{1.21})^{3.5} \div (1.1)^{-4.5} \times (1.331)^{2} = (1.1)^{? - 3}$

Convert all bases to $1.1$: $\frac{13.31}{1.21} = \frac{(1.1)^3}{(1.1)^2} = (1.1)^1$ So, $[(1.1)^1]^{3.5} = (1.1)^{3.5}$. Next, $\div (1.1)^{-4.5} = \times (1.1)^{4.5}$. $(1.331)^2 = [(1.1)^3]^2 = (1.1)^6$. Left side: $(1.1)^{3.5 + 4.5 + 6} = (1.1)^{14}$. Right side: $(1.1)^{? - 3}$. Equating exponents: $14 = ? - 3 \implies ? = 17$.