Factorise $5xy-20y$. Answer ... Use set notation to describe the shaded region. Answer ... On the Venn diagram, shade the region which represents $A\cup B'$. Answer

1. Identify and extract the common factor.

Both terms $5xy$ and $20y$ have a common factor of $5y$.

$5xy-20y=5y(x-4)$

1. Describe the shaded part of the Venn diagram in set notation.

The shaded region is inside $A$ but outside $B$.

Hence the region is
$A\cap B'.$

1. Identify the regions represented by $A\cup B'$.

$A\cup B'$ means the region in $A$ or in $B'$. So shade all of circle $A$ and all regions outside circle $B$. Equivalently, leave only the part in $B$ but not in $A$ unshaded.