The relationship between antioxidant food consumption per day in cups and the BMI of an individual is modeled by the following line of best fit: y = - 1.2x+26. Interpret the slope and intercept of the trend line within the context of the data.

This is in gradient intercept form (or slope intercept form)

y = mx + b

in this case y = - 1.2x + 26

so m (the slope) = - 1.2

and the y intercept = 26

I'm not sure what intercept they're asking for.

if you wanted to find the x intercept, just substitute.

y = 0 and find x.