Well done!

The trick is to notice the word *identical*.
Students who fail to take note of it will find this impossible to solve.

Is your child brilliant at Math?

cryotosensei

The unshaded part is simply the difference between 

It's divided by two because the unshaded area is missing in 

science

Are you smarter than a 12-year-old? Area

This is simpler than it looks.

The area of each triangle is $$\frac{15*20}{2} = 150$$.

The unshaded part is simply the difference between $$\frac{2*150-230}{2} = 35$$.

It's divided by two because the unshaded area is missing in **both** triangles.