First line:
System.out.println("Result: " + 2 + 3 + 5);
String concatenation is produced.
Second line:
System.out.println("Result: " + 2 + 3 * 5);
3*5 is calculated to 15 and is appended to string 2. Result 215.
The output is:
Result: 235
Result: 215
Note #1:
To produce an arithmetic result, the following code would have to be used:
System.out.println("Result: " + (2 + 3 + 5));
System.out.println("Result: " + (2 + 1 * 5));
run:
Result: 10
Result: 7
Note #2:
If the code was as follows:
System.out.println("Result: " + 2 + 3 + 5");
System.out.println("Result: " + 2 + 1 * 5");
The compilation would fail. There is an unclosed string literal, 5", on each line.