This is such a simple problem but I'm absolutely flabbergasted on how to do this.

I have 3 cells, A1, B1, C1. A1 & B1 are the two numbers for the equation with C1 being the final answer. In cell A2, I want to have a data validation list of +, -, *, / and whatever is selected in cell B2 will show the answer in C1.

For Example:

A1 = 300
A2 = +
B1 = 250
C1 = 550

A1 = 300
A2 = *
B1 = 20
C1 = 6k

etc etc.

What formula would I put in C1?