What is the area of the shaded region? ?

Hi!

The area of the shaded region is
The area of the whole triangle - the area of the smaller triangle

So first let's find the area of the whole triangle. 
a = 0.5bh
a = 0.5·5·12
a = 2.5·12
a = 30

Now find the area of the smaller triangle.
a = 0.5bh
a = 0.5·3·4
a = 1.5·4
a = 6

30 - 6 = 24

The answer is 24mm

Hope this helps! :)
-Peredhel

Cbecause they are equal so that means it is the same on both sides? ! hope this