Strontium-90 has a half-life of about 28 years. Which equation will solve the problem of how many grams of a 40 g sample will remain after 84 years?
Oy = }(40)
y = {(40)
Oy = 40(1)
y = 40()
84

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.