Every three years the population of one part of Brooklyn is recorded. In 2014 there was a population of 10,500 people.
From 2014 to 2017 the population increased by 22%.
From 2017 to 2020 the population decreased by 10%.
What was the population of this area in 2020?

Given: ae ≅ ce ; de ≅ be prove: abcd is a parallelogram. we have that ab || dc. by a similar argument used to prove that △aeb ≅ △ced, we can show that △ ≅ △ceb by. so, ∠cad ≅ ∠ by cpctc. therefore, ad || bc by the converse of the theorem. since both pair of opposite sides are parallel, quadrilateral abcd is a parallelogram.