Question 862718
let the erect part of the pole be x 

the slanted part of the pole will be 18-x

the ground distance = 12 

they form a right triangle

apply Pythagoras theorem

12^2+x^2=(18-x)^2

144+x^2=324-36x+x^2

36x=324-144

36x=180

x=180/36

x=5 feet