Question

Have no idea how to do it

Answer 1

$\bf 2)\\\\ 3+-5\implies 3+(-5)\implies 3+(-3-2)\implies ~~\begin{matrix} 3-3 \\[-0.7em]\cline{1-1}\\[-5pt]\end{matrix}~~-2\implies -2 \\\\\\ 9)\\\\ -5+(-6)\implies -5+(+5-11)\implies ~~\begin{matrix} -5+5 \\[-0.7em]\cline{1-1}\\[-5pt]\end{matrix}~~-11\implies -11 \\\\\\ 11)\\\\ 2+(-7)\implies 2+(-2-5)\implies ~~\begin{matrix} 2-2 \\[-0.7em]\cline{1-1}\\[-5pt]\end{matrix}~~-5\implies -5$