Answer:
The formula for area of a parallelogram is A=bh
x=10.3
Explanation:
We don't have the base but we have the height.
the base is x and the height is 5
if the area is 51.5
we should divide the height to find the base.
51.5÷5=10.3
so the base is 10.3
Check if answer is correct:
b=10.3
h=5
a= 51.5
10.3(5)=51.5
a= 51.5cm²
I hope this helps as long as you know the formula it's easy :D