Alright, Victoria, let's make this easier.
So, we can break down what's under the radical into factors.
√8 = √(4(2)) = √4√2
What's the square root of 4? 2. We already have a 2 in front of 2√8, so...
2√8 = 2(2)√2 = 4√2
6√50 = 6√(25(2)) = 6√25√2 = 6(5)√2 = 30√2
Now, just like 4x + 30x = 34x...
4√2 + 30√2 = 34√2
Hope this helps!