Read the description of a proportional relationship.
In The Tall Tales of Timothy Toad, a witch brews a magical invisibility potion. There is a proportional relationship between the amount of potion the witch drinks (in milliliters), x, and the amount of time she is invisible (in minutes), y.
The equation that models this relationship is y=4x.
How much potion does the witch drink to be invisible for 16 minutes? Write your answer as a whole number or decimal.
