4pi=w-6pi

4 pi = w - 6pi

w = 4 pi + 6 pi            =>  w  = 10 pi  = $${\mathtt{10}}{\mathtt{\,\times\,}}{\mathtt{\pi}} = {\mathtt{31.415\: \!926\: \!535\: \!897\: \!932\: \!4}}$$