What is the percent decrease from 25 to 15?

If anyone has done the algebra 2 chaos theory portfolio would you be wiling to me? i kind of know what i'm doing i just don't know if i'm doing it right.

Seymour is twice as old as cassandra. if 16 is added to cassandra’s age and 16 is subtracted from seymour’s age, their ages become equal. what are their present ages? show !

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