help please

Erica created the following graph that looks at how working affects student marks. Impact of Work on Marks y=-1.3375x + 91.801 R2 = 0.6194 100 90 80 Mark (Average) 70 60 50 0 2 6 8 10 12 14 16 18 Hours Working per Week a) Determine the coefficient of determination and interpret its meaning. b) Determine the correlation coefficient and interprets its meaning. c) Predict the mark of a student who works 18 hours per week