15 feet to 33 feet
Identify the percent of change as an increase or a decrease.
In this problem we have that
15 ft ------> represent 100%
Find out the difference (33-15=18 ft)
so
Applying proportion
Find out how much percentage reprrsent the difference of 18 ft
100/15=x/18
solve for x
x=(100/15)*18
x=120%
therefore
the answer is 120% (percentage of increase)