Step-by-step explanation
Let's assume that a certain quantity q increases or decreases until it reaches a value q'. Then the absolute change is given by:

On the other hand the relative change is given by dividing the absolute change with the original value:

In this case the original quantity is the population of Cleveland in 2007 and the increased/decreased quantity is the population of the city in 2017. Therefore we have q=440358 and q'=385525. Then the absolute change is:

The relative change is given by:

As a percent the relative change is:

Answer
Then the answers are:
Absolute change: -54833
Relative change: -12.45%