Answer:
highest: $1,438
lowest: $1,062
Explanation:
The highest and lowest points are adding $188 and subtracting $188 from her brother's amount.
So, to find the highest point, add $188 to $1,250, which is $1,438.
To find the lowest point, subtract $188 from $1,250, which is $1,062.
Hope this helps ;)