I think it's most likely Euler's method...
Euler method - Wikipedia, the free encyclopedia but I could be wrong.
This is a Euler's Method problem as Deadstar stated.
If you need to relearn how to do this I suggest watching this lecture:
Lecture 2: Euler's Numerical Method for y'=f(x,y) and its Generalizations
You need to do two steps to get to that point.