Answer:
the answer is 108 ft²
Step-by-step explanation:
multiple 18 to 6
Ok so in order to find the answer to this problem we are going to Multiply

and

.
You can answer this problem using the midpoint formula, but we can work out the 4th vertex by just logically thinking it through by first drawing out the rhombus on an x-y coordinate plane. I wrote the answer out on paper since it is easier than typing. Let me know if you have any questions.
I think it’s 17 cause 51/3 is 17.