Selection C is the appropriate choice.
The slope-intercept form: y = mx + b
m - a slope
y = 5x + 2/5
Answer: The slope m = 5.
If popcorn is p and water is w the equation can be written as
3p + w = 9.25
because there was 3 boxes of popcorn and one water (hence the coefficients) and the total is 9.25
then plug in 1.75 for w the price of water:
3p+ 1.75 = 9.25
you can move stuff around algebraically now (subtract 1.75 on both sides and divide by three on both aides) to get the cost of one box of popcorn (p).
The answer is 2.50