Add Function with 5 Numbers

Im new to TypeScript and would like to try out a few examples, but it seems like I do stuck at one of them.

 

I'd like to write a function with 5 numbers which can be inserted by the user. From those 5 numbers, the second, third and fourth number should be summed up.

 

The result should be invoked via a variable named result.

 

 Does anyone know how to do it?