Answer
See the explanation
Work Step by Step
A string in the context of this syntax diagram is defined as a sequence of characters.
We want to parse xxyxx according to String -> x String x | y.
Start with String = x String x (since it starts with x).
Remaining string inside: xyx. Again, it starts with x, so String = x String x.
Remaining string inside: y. This matches the base case String -> y.
Now, we can draw the parse tree )+(see figure).
