Help me answer this, thank you

4

Step-by-step explanation:

P={1,2,3,4,5,6}

Q={3,4,5,6,7,8,9}

PnQ={3,4,5,6}

Therefore, n(PnQ) =4

definition: a circle is the  set of all points in a plane that are equidistant  from a given  point  called the center of the circle. we use the symbol ⊙ to represent a circle. the a line segment from the center of the circle to  any point  on the circle is a radius of the circle.

step-by-step explanation:

i googled it and this is what i got i don't know how it is. sorry.