Let x = number of long sleeve shirts
Let y = number of short sleeve shirts
x + y = 200
x/2 + y/3 = 80
Now solve this pair of simultaneous equations to find x and y.
You can tell straight off the bat, it does have a solution, and it isn't infinite solutions. If it had no solution, it would have the same slope but different y-intercepts. If it had infinite solutions, the 2 equations would have to be the exact same. So there is only one solution.
