At the city museum, child admission is $6.00 and adult admission is $9.40. On Monday, four times as many adult tickets as child tickets were sold, for a total sales of $1613.20. How many child tickets were sold that day?

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.