SELECT  COUNT(result_answerid) AS MAX,(SUM(result_answer_iscorrect)/2) AS score FROM (SELECT * FROM ph_results_answers WHERE questionid IN (SELECT questionid FROM ph_tests_questions WHERE testid=28) AND resultid=250 ) a  INNER JOIN ph_questions b ON a.questionid = b.questionid WHERE question_diff = 3

UNION ALL

SELECT  COUNT(result_answerid) AS ABC ,(SUM(result_answer_iscorrect)/2) AS CDE FROM (SELECT * FROM ph_results_answers WHERE questionid IN (SELECT questionid FROM ph_tests_questions WHERE testid=28) AND resultid=250 ) a  INNER JOIN ph_questions b ON a.questionid = b.questionid WHERE question_diff = 2 OR  question_diff = 1

MAX score
1   1.0000
3   2.0000