Explain why 138 is divisible by 3

The figure shows triangle def and line segment bc, which is parallel to ef: triangle def has a point b on side de and point c on side df. the line bc is parallel to the line ef. part a: is triangle def similar to triangle dbc? explain using what you know about triangle similarity. part b: which line segment on triangle dbc corresponds to line segment ef? explain your answer. part c: which angle on triangle dbc corresponds to angle f? explain your answer. asap

I'm confused on how to solve the triangle. can someone me ?

Me. brady is putting trim around the edge of circular merry-go-round that has diameter of 15 feet. how much trim does he need to buy to the nearest tenth