What is the range of this function ??

Use the knowledge of x- and y- intercepts to choose the correct graph of the equation 3x+6y=6

Asurvey of 45 teens found that they spent an average of 25.6 hours per week in front of a screen (television, computer, tablet, phone, based on the survey’s sample mean, which value could be the population mean? 2.3 hours 27.4 hours 75.3 hours 41.5 hours

How do i simply this expression (quadratic formula basis) on a ti-84 or normal calculator?