How to write a quadratic function given the roots and y intercept?

Tim open up a new saving account with a $50 deposit and plant to deposit $20 per week into the same account. write an expression to represent the total amount in his savings account.

I'm a polygon i have no parallel lines i am formed 3 line segments i have one right angle two of my angles are angles what am i

Answer asap! urgent! will give brainliest!