It would help if you could specify what the area is in total, in order to find the perimeter with a variable.
So for this, we will be using dimensional analysis:

In short, he should receive ¥8835.30.
Six over eleven the answer to this problem.
Using Pythagoras:-
x^2 = 6^2 + (sqrt18)^2
= 36 + 18 = 54
x = sqrt54 = 3 sqrt6
3. is the answer, as you can see D is one and a half units to the right of the y axis at a height of 3 units and C is one and a half units to the left of the y axis with the same height. So D is "reflected" about the y axis and only the x coordinate changes sign from positive to negative.