So, first let’s see how much income she makes in 28 days. To do this we multiply 78$ by 28, which gives us 2184. Now we need to calculate the total of her expenses, how much money she spends. She spends 8 dollars per day at lunch, and 6 dollars per day to and from work. So let’s add 8 plus 6, and we get 14. Now let’s multiply 14 by 28 which gives us 392. Now we subtract 2184 minus 392, and we get 1792. So our answer is 1792$