(27²-23²)/(31²-19²)=(27-23)(27+23)/[(31-19)(31+19)]=4*50/(2*50)=2
(52²-48²)/(64²-36²)=(52-48)(52+48)/[(64-36)(64+36)]=4*100/(28*100)=1/7
(32²-34²)/(22²-44²)=(32-34)(32+34)/[(22-44)(22+44)]=(-2*66)/(-22*66)=1/11
(45²-41²)/(31²-55²)=(45-41)(45+41)/[(31-55)(31+55)]=4*86/(-24*86)=-1/6
(67²-33²)/(43²-77²)=(67-33)(67+33)/[(43-77)(43+77)]=34*100/(-34*120)=-5/6
(4²-56²)/(66²-34²)=(4-56)(4+56)/[(66-34)(66+34)]=(-52*60)/(32*100)=-39/40