#### Answer

$35.5$ ft

#### Work Step by Step

Since the triangles are similar, we can set up a proportion between the sides of the small and large triangles:
$\displaystyle \frac{y}{45~ft}=\frac{1~ft}{1.5~ft}$
Cross-multiply and solve for $y$:
$1.5y=1*45$
$y=45/1.5$
$y=30$ feet
To find the height of the tree, we need to add the given height of $5\frac{1}{2}$ ft to $y$:
$5\frac{1}{2}+30=5.5+30=35.5$ ft