Can y’all help me on question 17?!

Answer:
18 ft
Step-by-step explanation:
5 years for every 3 feet
30 years
Knowing this information, we can multiply or create an equation:
Multiplication:
5 x 6 = 30 so...
3 x 6 = 18
Equation:
5/3 = 30/x
5x = 90
/5 /5
x = 18