There are no given ages for either of them, but Gogo is listed as an "industrial engineering student" and Honey is listed as a "chemistry student". These are titles used to denote someone's college major.

Put simply, the stuff Disney gave us so far suggests that they are both in college. The thing is though, that doesn't necessarily mean they are adults. Hiro is in college as well, and he is 14. He's a genius. So are Honey and Gogo, so who knows? They could be the same age as him.

But, I'm willing to bet that they are both at least 17 years old.