There are frogs and koi in a pond and the number of frogs and the number of koi in the pond are independent. Let the x represent the number of frogs in any given week, and let y represent the number of koi in any given week. X had a mean of 28 with a standard deviation of 2.7, and y has a mean of 15 with standard deviation of 1.6. Which answer choice correctly calculates and interprets the standard deviation of the difference, D=X-Y?

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