Final answer:
Vivian's grandfather uses 5 cups of pecans for every 50 pralines, leading to the proportional relationship equation: y = 10x, where y is the number of pralines and x is the amount of pecans in cups.
Step-by-step explanation:
The question asks us to establish the proportional relationship between the amount of pecans used (x) and the number of pralines made (y). Given that 5 cups of pecans make 50 pralines, we can derive the constant of proportionality (k) by dividing the number of pralines by the number of cups of pecans.
k = y/x = 50/5 = 10
Therefore, the equation expressing the relationship between x and y is:
y = 10x