X + (X+1) + (X+2) = 170 this is setting the first number equal to X, so it makes sense that X+1 is the number above it, and X+2 is 2 numbers above it.
3X + 3 = 170 now solve for X
3X =167
X = 55 2/3 now you need to add 1 and 2 to that answer to get the next 2 numbers.
So 55 2/3, 56 2/3, 57 2/3
It appears as though there are no 3 consecutive natural numbers that when added together are equal to 170.