19.8 m
We have 2 similar triangles. For the 1st triangle, we have two legs, one being the man's height of 1.8m and the second being the length of his shadow at 6m. So we have the ratio 1.8/6. The other triangle is comprised of the pole's height and length of the pole's shadow which will be 60m + 6m = 66meters. So we have another ratio of x/66 which has the same value as the first ratio. So let's solve for x.
1.8/6 = x/66
66*1.8/6 = x
11*1.8 = x
19.8 = x
So the light pole is 19.8 meters tall.
