7. Consider the following method: public static int mystery (int x, int y) ( if (x < 0) { } return mystery (-x, y); else if (y < 0) { return mystery (x, y); else if (x--0 && y==0) { } else { return 0; return 100 mystery (x/10, y/10)+10 (x810) + y 10; For each of the following calls, indicate the value that is returned: a. (2 pts) mystery (5, 7); b. (2 pts) mystery (-7, 4);