How to manage basic algorithm using Excel 2007

I really don’t know how to explain what I’m looking for so I’ll just try my best with this.

At work, I usually use a long calculation based on Salary and the period an employee has in the company. It’s a simple calculation; the first 5 years are with half the salary so basically 5 X Salary X ½ and the rest are multiplied with a full salary.

For example,

1) Let’s say James has 15 years with a $50,000/year salary contract in the company.

So,

- 5 years X $50,000 X ½ = $125,000
+
- 10 Years X $50,000 = $500,000

Therefore, Total = $500,000 + $125,000 = $625,000

Another Example will be using Months which is somewhat complicated.

Example,

2) Andrea has a 15 Years and 4 Months with a $50,000/year Salary contract in the company.

So,

- 5 years X $50,000 X ½ = $125,000
+
- $50,000 X [10 Years + 4 Months (4/12)] = $50,000 X [10.3333333333333] = $516,666.67

Therefore, Total = $516,666.67 + $125,000 = $641,666.67

One last example which is also a bit complicated.

3) Tom has a 4 Years and 6 Months with a $50,000/year salary contract in the company.

So,

- [4 years + 6 Months (6/12)] X $50,000 X ½

Therefore, Total = [4.5] X $50,000 X ½ = $112,500

That’s as clear as I can explain it. I know there is this simple way on Excel 2007 where these calculations can be done easily and simple but I don’t know how. I hope someone can help me out.

But what about the years?? The years arn't defined in your equation.

GOt IT and it worked!!.. Thanx so0o much.. =D