I hope it's clear enough.
your answer would be -2.57142857143
16 servings
because there are 4 cups in a quart, and two quarts is 8 cups.. if 5 cups of milk makes 10 servings there is half a cup in each serving.. so 8/.5 is 16
Since it is perpendicular to y=3x-1, the slope must be a negative reciprocal.
there the slope of the perpendicular line is

So now we have,

To find b, we use the point that the line passes through and substitute it to the y and x values.

which would give us b=5/3
Therefore, the equation of the line is
The sum of b and f is b+f
Three times this sum is 3(b+f)