Area of a lake is 9/20 a square mile. the width is 1/5 the length. what is the length and the width.

Say, length =x mileWidth =.  x/5 milex*x/5=9/2020x*x=45x*x=45/20      =9/4x=3/2 mileLength =3/2 milesWidth=. 3/10 miles

Yes, It would be reasonable since thats about the weight of a skateboard.
However, the average skateboard is closer to 6 pounds. So, the skateboard in the question is very possible- but it would be really low quality.

However- given that you are in middle school- I would say yes, it is reasonable.