We can post the question using the following equation:
Nelly makes $8 an hour, but she needs to pay her mother back $7. This is the first part of the equation. She needs to have $49 at the end. So, to solve the equation, we have:
We add 7 to both sides of the equation. Now, dividing both sides by 8, we finally have the result of x.
Therefore, she needs to work for 7 hours to pay her mother $7 and has $49 in her account. (In your options Ob = 7).