Answer: The equation to find the number of doughnuts that Jane had is
3 + 2x = 15.
Explanation:
Let the number of doughnuts that Jane had be x.
It is given that Jim had three more than twice the doughnuts that Jane had.
Therefore, Jim had (3 + 2x) doughnuts.
According to the given problem, the equation becomes
3 + 2x = 15
The problem can be solved by applying this equation to find the value of x.