Let x = the number of hours Naomi worked
Let y = the number of hours Hudson worked
Using the numbers they gave us regarding how many shirts each of them can iron per hour, you multiply the number of shirts Naomi can iron per hour by x (the number of hours Naomi worked), and vice versa for Hudson. Combined, they ironed 395 shirts. That is what it will be equal to.
Combined, they worked 13 hours. You dont know how many hours they each worked, so it becomes x + y = 13.
Here is your system of equations:
35x + 20y = 395
x + y = 13