We're finding the equivalent value to 3/4. So 3/4 would be equal to or equivalent to 12/16. We know this because 12/16 simplified = 3/4. So since 3/4 is equal to 12/16, that means it would take us 12 tablespoons of butter to make the banana bread.
In order to find the slope, you need to find the difference in the x values and the difference in the y values. To do this, you write out y2-y1/x2-x1, insert your x and y values, and get your answer. Then, you find your y-intercept (where the x value is 0).