We can post the question using the following equation:
![8x\text{ - 7 = 49}](https://img.qammunity.org/2023/formulas/mathematics/college/fvhiez1v12plbdxppvvdf6p5c4qw2vgxop.png)
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:
![8x\text{ = 49 + 7 = 56}](https://img.qammunity.org/2023/formulas/mathematics/college/pen84m4i40ip5y1mt1iora02cad27caaw4.png)
We add 7 to both sides of the equation. Now, dividing both sides by 8, we finally have the result of x.
![(8x)/(8)=\text{ }(56)/(8)=\text{ x = 7}](https://img.qammunity.org/2023/formulas/mathematics/college/d7boz77qv2pjim6bu7xfsbbt1s781u6ow2.png)
Therefore, she needs to work for 7 hours to pay her mother $7 and has $49 in her account. (In your options Ob = 7).