The answer is an average rate of change of 110 more dollars in her account per week. You find this by first subtracting the starting amount of 250 from the end amount of 800 that equals 550. then you divide that number by five, the number of weeks, to get the average rate of change.
Check the picture below.
so... you can pretty much see how long RS and QT are, you can just count the units off the grid.
now, let's find QR's length

and let's also find the length for ST

so, add the lengths of all sides, and that's the perimeter of the trapezoid.
I think answer should be 21