Firstly, you'll want to form an equation:
a+b+c=d
To make it simpler, let's just say that 'a' is the largest integer
In that case, d-50=a
I could give you some convoluted equation to find your integers but honestly, checking and guessing is easier.
I just ran through a couple sets of numbers in my brain, although I'd suggest actually writing down your thought process.
These are the integers I got:
20, 30, and 50
Keep in mind, however, that there are multiple correct answers to this problem.