H and K is similar. You can see that H has been enlarged to get K.
This one, you need to find the scale factor of the enlargement (how much its been enlarged by)
To find this all you need to do is find how much one of the sides have been enlarged by, in shape H the top angle 5cm turned into 15cm. This means the scale factor is 3, because 5 x 3 is 15.
Do this for 8 to find the side of shape K.
8 x 3 = 24
Now use the formula base x height to find the area of the rectangle K.
base = 15 (top and base of a rectangle are the same)
height = 24cm
area = 15 x 24 = 360cm²
Area = 360cm²