how do you solve this?

Answer:
length = 1
area=13.5
Step-by-step
x is
28-2x=1
=>-2x=1-28
=>-2x=-27
=>x=-27/-2
therefore
x=13.5
The common difference between the length is -2
So the length is
26+(13.5-1)×-2
26+12.5×-2
26-25
1
So the area is
13.5×1
13.5