Its the connection between those numbers
1. 6:3
2. 6:2
3. 3:18
4:5:6
5:13
6:x
7:x
8: check
9:check
10: x
The internal angle sum of a quadrilateral is :
C. 360°
The sum of internal angles of a polygon is determined by a formula :

where n represents number of sides.
In a quadrilateral there are four sides,
So, plugging 4 in the formula :
_____________________________

I did this manually on some notepaper but my scanner is not working.
The answer is 72 cm^2