Evaluate (9+5--6)(5+-6)

Replace all occurrences of ${\displaystyle -}$${\displaystyle -}$ with a single ${\displaystyle +}$. Two consecutive minus signs have the same mathematical meaning as a single plus sign because ${\displaystyle -1\cdot -1=1}$

Replace all occurrences of ${\displaystyle +}$${\displaystyle -}$ with a single ${\displaystyle -}$. A plus sign followed by a minus sign has the same mathematical meaning as a single minus sign because ${\displaystyle 1\cdot -1=-1}$

Add ${\displaystyle 9}$ and ${\displaystyle 5}$.

Add ${\displaystyle 14}$ and ${\displaystyle 6}$.

Subtract ${\displaystyle 6}$ from ${\displaystyle 5}$.