Easy,
If one of the small rectangles area is 12 and its side length is 4..
12/4=3
So the length and width of the small rectangle are length=4 width=3.
For the NEW rectangle take..
12*6=72
That means the NEW rectangles Area is 72 sq. cm.
To find it's Perimeter...
For 1 small triangle take 3+3+4+4=14 (P=l+l+w+w)
Since there are 6 small rectangles take 14*6=84
Thus, the perimeter of the NEW rectangle is 84 cm.
All together the Area and Perimeter of the Rectangle is...
A= 72 sq cm
and
P=84 cm