Before solving this type of question, we should remind ourselves of the ‘CDPEU’ chart, then find the right direction for solving this kind of question. According to the chart, this question is a trinomial one. The first part() and the last part(30) always provides informtaion. For example, if we want to find the factor of this one, we need to look at the first part and the last part. The last part is 30. 30=3 × 10=2×15=5×6, the middle part is -11x. Due to -11, we can eliminate 3&10, 2&15 becasue regardless of adding or substracting, 3&10 or 2&15 still can not get the answer of 11. There is only answer: 5&6 becasue 5+6=11, but there is one thing very important is that the number is -11(it’s negative). The last part is a postive 30, so the final answer is -5&-6.