Commutative Ring Where Each Element is its own Inverse

Question

I need help with the following problem:

Let $R$ be a commutative ring. Show that if $1+1=0$ in $R$, then $a+a=0$ for every element $a$ in $R.$

I am not really sure where to begin, so any direction or help is appreciated! Please and thank you.

Answer 1

Hint : $a+a = a \cdot 1 + a \cdot 1 = a\cdot(1+1)$.