How can I solve this?

The 3 inside angles need to equal 180 degrees.

Angle K is given as 48 degrees.

Angle M would be 90 degrees.

Angle J = 180 - 90 - 48 = 42

Angle J = 42 degrees

you have 6 cupcakes

the given 6 = w/p is equivalent to 6p = w, where w is the total area of the walls and p is the area covered by a single can of paint.

knowing that 6 cans of paint will be needed, 6p = w becomes 6(6) = w = 36.   this tells us that the total area to be painted is 36 square units.