Every Sunday, Chase and his friends get together to play their favorite board game, The Gems of Rawumba. Whoever collects the most gems wins! Players can earn gems by building mines.
There is a proportional relationship between the number of mines Chase builds, x, and the number of gems he earns, y.
x (mines) y (gems)
1 4
4 16
8 32
9 36
What is the constant of proportionality? Write your answer as a whole number or decimal.