With 14 and 15 i don't understand them

Which matrix can be multiplied to the left of a vector matrix to get a new vector matrix ?

Can someone me with the property questions for 12 13 and 14 plz

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