[tex]\huge\boxed{\sf 16}\\\\ \sf The\ two\ right\ triangles\ are\ a\ reflection\ of\ each\ other.\\ Both\ sides\ are\ equal\ in\ size. \\\\ 5x+1=4x+4\\5x-4x=4-1\\1x=3\\\\ Plug\ the\ value\ of\ x\ back\ into\ any\ of\ the\ two\ equations.\\\\ 5(3)+1 =15+1=16[/tex]
