The roster form of a set is the elements listed inside brackets { }.
In this case it is easy to visualize A - B directly of the Venn diagram: when you subtract from A those elements that are also in B, the result is A - B = {4, 11, 14}.
Now take into account tha (A - B)' is the complement of (A - B), this is all the elements that are not in A - B.
Being A - B = {4, 11, 14} then to show (A - B)' you just have to list all the elements that are on the figure except 4, 11 and 14.
The result, in roster form, is (A - B)' = {1, 2, 3, 5, 6, 7, 8, 9, 10, 12, 13}
We have been given a histogram, which represents the plant species spotted in the animal reserve.
The x-axis represents the number of plant species and y axis represents the number of map squares.
We can see that 0 to 9 species are spotted in 1 map square.
10 to 19 and 20 to 29 plant species are spotted in 2 map squares.
To find the number of map squares that spot more than 29 plant species, we will count number of map squares that spot 30 to 49 plant species as 30 to 49 numbers are more than 29.
We can see from our histogram that 4 map squares spot 30 to 39 plant species and 6 map squares spot 40 to 49 plant species.
Therefore, 10 map squares spot more than 29 plant species.