Hi Jauvy, let me try to help you out with the question and provide some explanation as well.
This question makes use of model manipulation.
As you can see in my ‘before’ model, Abigail and Peiying had the same amount of money, as represented by the same length of boxes for each of them.
In the ‘after’ model, after both of the girls have spent the respective amounts, we can see that Abigail has 15 units while Peiying has 1 unit. This tells us that Abigail has 14 units more than Peiying in the end.
Now, we know that Peiying has spent $627 while Abigail has spent $277. This tells us that Abigail has spent $350 less than Peiying, so Abigail will actually have $350 more left, compared to Peiying.
In the end, Abigail should have $350 more than Peiying, and this is represented by the 14 units more as worked out previously.
14 units equals $350
1 unit equals $25
Peiying had at first:
1 unit + $627, which works out to be $652.
Hope this solution provided above helps!
Feel free to PM or text me (: