so a easy way to do it is to split the sides up find the area for each and then add it all up
1) the first side is 9*9=81 b.c. it is base times hiehgt (area formula).
2)another is 10*9 =90 b.c its base times height
3)another is 9*13.5 =121.5
NOW you have the triangles left which is (base times height)/2
4)9*10=90/2=45
5)(the same as #4)
then add up all the areas we found.
81+90+121.5+90 = 372.5 in^2