Which inequality will have a shaded area above its graph

2x − y ≥ 4
4x + 3y < 6
x − 9y ≤ 1
x − 3y > 4

2x-y≥4

-y≥4-2x

y≤2x-4  so this area is below the graph

..

4x+3y<6

3y<6-4x

y<(6-4x)/3  so this graph is below the graph

..

x-9y≤1

-9y≤1-x

y≥(1-x)/9  So this area will be above the graph (and include the line itself as well)

..

x-3y>4

-3y>4-x

y<(4-x)/3  is an area below the graph

..

So the only inequality having a shaded area above the the graph is:

y≥(1-x)/9, or in its original form

x−9y≤1

The answer is, the streetlight is 18 inches tall.