What is a good system of equations word problem?

Question

I am doing my Algebra project and I need help coming up with a system of equations word problem.

Answer 1

There are hundreds! Thousands!

Try this one:

The sum of 2 number is 12 and the difference of the same 2 numbers is 5. What are the numbers?

or this one:

I have 10 coins in my pocket, all nickels and dimes. In total I have 65 cents.

How many of each coin do I have?