Question 1010273
Yes.  If the width is 10 and the length is three times that, you would say the length is 30.  If the width is 20, the length is 60.  Right?
So, if the width is y units, the length is three times that too, or 3y units.
Then the area is always length times width, and
A = LW = (3y)(y) = 3y^2 square units