Acinema sells adult tickets and child tickets.

the total cost of 3 adult tickets and 1 child ticket is £30
the total cost of 1 adult ticket and 3 child tickets is £22

work out the cost of an adult ticket and the cost of a child ticket

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.