Open Question: my moms dog is matted and very old. how do i get them out?

17-18 years of age my mother's dog. It's a shitzu poodle mix long curly hair. The poor thing is jumbled Vail his hind legs, he received the fur was arrested, he crystallization. : (. I want to bathe him brush his ñ ñ crystallization, even simple things, he .., I cut for immediate thinkin to cut him. But Lin did not know how I would go about it, because he is so wrapped around the old knot. I tried to call the local caregivers, they want money, I cannot afford. So, I should brush, and then cut bath him? or a bath, brush, dry, interrupted him? IDK's how to do it.