Hello ^^

Please help me solve this. This might appear a little too easy for those of you who are pros but still .. It's 24th ex. and everything that was before and after this turned out quite easy for me. But for some reason I got stuck with this one :/

Since I doubt I can translate the contest of the exercise decently, I scanned whatIwrote. I hope you can understand the symbols at least? I mean, isn't maths the international language and all I did start and I did try but kjaskjgkagf

Therefore, I hope you can help me^^~~~

P.S. for Area (A), in my country we use symbol (S). And in case it's not obvious (because damn I'm not good at drafting) enough, it's a parallelogram