$-14+i-\left( -12-11i \right)$
When there is a $-$ in front of an expression in parentheses, change the sign of each term of the expression and remove the parentheses$-14+i+12+11i$
Calculate the sum$-2+i+11i$
Collect like terms$-2+12i$
Write the complex number in absolute value bars$|-2+12i|$
Use $|a+bi|=\sqrt{ {a}^{2}+{b}^{2} }$ to calculate the modulus$\sqrt{ {\left( -2 \right)}^{2}+{12}^{2} }$
Simplify the expression$\begin{align*}&2\sqrt{ 37 } \\&\approx12.16553\end{align*}$