$$ \begin{array}{1} \text { There are } 350 \text { students in a class. Each of them takes a test with three questions } \mathcal{Q}_{1}, \mathcal{Q}_{2}, \mathcal{Q}_{3} \text { Each student answers at least } 1 \text { question. There are } 260 \text { students who answered } \mathcal{Q}_{1}, 100 \text { who answered } \mathcal{Q}_{2} \text { and } 70 \text { who answered } \mathcal{Q}_{3}, 40 \text { students answered } \mathcal{Q}_{1} \text { and } \mathcal{Q}_{2}, 40 \text { students answered } \mathcal{Q}_{2} \text { and } \mathcal{Q}_{3} \text { and } 30 \text { students answered } \mathcal{Q}_{1} \text { and } \mathcal{Q}_{3} . \text { Find } A \text { the } \text { number of students who answered all questions and } B \text { the number of students who answered either question } \mathcal{Q}_{2} \text { or } \mathcal{Q}_{3} \text { or both. } W A=\square \quad \square \quad \square \quad \text { For sets } A, B, A \cup B eg A \text { implies that } B subseteq A \text { } B \text { For arbitrary sets } A, B, C \text { we have } A \cap(B \cup C)=(A cup B) \cap (A \cup C) \text { } \text { Decide which of sets } A, B, C \text { we have } A \cup(B \cap C)=(A \cap B) \cup (A \cap C) \text {. } \square \text { For subsets } B, C \text { of } A \text { we have } A \backslash(B \backslash C)=CA \backslash B) \backslash C \text {. } \end{array} $$ SP.PB. 099