Please answer me 2 questions below with details explanations and calculations. thanks so much!

TABLE 1.7 Brand AT&T AT&T Panasonic Panasonic Uniden Uniden Vtech Vtech Data for Eight Phones Model CL84100 TL92271 4773B 6592T D2997 D1788 DS6521 cs6649 Price (S) 60 80 100 70 45 80 60 50 Overall Score 73 70 78 72 70 73 72 72 Voice Quality Excellent Very Good Very Good Very Good Very Good Very Good Excellent Very Good Talk Time (hours) 7 7 13 13 10 7 7 7