Liam opened a savings account with a $400 deposit and a simple interest rate of 7.5%. If the balance of the account is now $670 and there are no deposits or withdraws, how long ago did he open the account?

How to do this , and can some one explain

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.

Use the second shift theorem to find the inverse laplace transform of (e^−3s) / (s^2 + 2s − 3)