Question 1085
Let Tree's height = T
Let Tree's Shadow = Ts = 18'
My 6' shadow produced by my 5'2" height
Tree's 18' shadow is produced by Tree's ((5'2")/6)*18 = (5'2")*3 = 15'6" 

Ans for height of Tree is 15.5' since 12" = 1'.

If Building across other street  is 30' tall,

And my 5'2" height produced 6' shadow,
then building's 30' will produce (6/(5'2"))* 30 = 180/(5'2")  

= 180/(31/6)
= ((180 * 6) /31)