Well the first three is in this place value _ - _ _ where the dash is i that is hundred second one is tens
You have known the formula Length of base is la division of Area and a haft of the height.
So we have 3

or


and

have fun
Well the formula is : b1+b2/2 (h)
so the height would be solved as :
13.5 = 3+6/2 (h)
13.5 = 9/2 (h)
h = (13.5)/(9/2)
h = (13.5) x (2/9) *reciprocal*
h = (27) / (9)
h = 3