Over the summer, Springtown Science Academy renovates its building. The academy's principal hires Greta to lay new tile in the main hallway. This table shows the relationship between the length (in feet) of hallway Greta covers with tiles, x, and the number of tiles she needs, y.
x (feet)y (tiles)
2.530
3.542
672
784
According to the values in the table, do x and y have a proportional relationship?
yes
no
What is the constant of proportionality? Write your answer as a whole number or decimal.