Calculator and file handling

I’d like a simple yet polished mobile calculator app written in Python. It must do the everyday basics—addition, subtraction, multiplication and division—and also offer a graph-plotting screen where I can enter a function such as y = 2x + 3 and see the curve render instantly... (Budget: ₹12500 - ₹37500 INR, Jobs: App Development, Coding, Data Entry, Mobile App Development, Python)