WAEC - Mathematics (1997 - No. 3)
A and B are two sets. The number of elements in A∪B is 49, the number in A is 22 and number in B is 34. How many elements are in A ∩ E?
105
27
15
12
7
Vysvětlení
Let x represent the intersection
34 - x + 22 - x + x = 49
- x = 49 - 56; x = 7
34 - x + 22 - x + x = 49
- x = 49 - 56; x = 7