Let $GL_2(\mathbb{R})$ be the group of matrices with non-zero determinants, and let $H=\{I,-I\}$ be the subgroup of $GL_2(\mathbb{R})$ ; where $I$ denotes the identity matrix. Then what is the group $GL_2(\mathbb{R})/H$ ?
Actually I know the procedure. I have to find another group and an onto homomorphism between them such that $H$ becomes the kernel of that homomorphism. But I don't have any idea how to find such group OR homomorphism ?