Given that,

ABCD is rectangle

CD = 6 cm

AD = 8 cm

We know that,

If a rectangle and a parallelogram are on the same base and between the same parallels, then the area of a triangle is equal to the half of parallelogram

So, triangle GEF and parallelogram ABCD are on the same base and between same parallels, then we know

Area of parallelogram = Base * Height

Now,

Area ( = * Area of ABCD

= * AB * AD

= * 6 * 8

= 24 cm²

Hence,

Area ( is 24 cm²