Answer:
1. Sean
2. Mariana
Equations:
Sean: y=-5.5x+300
Mariana: t=-5x+250
For the first question, it is basically asking for who has a greater negative slope, which would be Sean, since he drank his faster.
For the second question, Mariana finished his slushy at the x-intercept of 50, while for Sean, it would be an estimated 54.5.