A 3-foot-tall mailbox casts a shadow that is 1.8 feet long. At the same time, a nearby street lamp casts a shadow that is 12 feet long. How tall is the street lamp?

20 feet tall

Step-by-step explanation:

If these are at the same angle, which i'm assuming they are, the following would happen:

Put length of 1 item over its shadows length equal to 2nd items length over its shadow. Put x in the place you want to find (Lamp in this case)

(3/1.8)=(x/12)

Cross multiply

36=1.8x

Divide by 1.8 on both sides

20=x