Answer :

JamieBoss
Use the proportion x/15 = 3/5 (height of object/length of shadow) and cross multiply. 5x = 45. divide both sides by three and x=9.
1/5 = x/15 solve for x
15 * 1/5 = 15/5 = 3
it is 3 yards tall

(I changed the 3 feet to 1 yard to keep the units the same)