Find the value of x in the triangle

In a class, there are 12 girls. if the ratio of boys to girls is 5: 4 how many boys are there in the class

What does independent variable and dependent variable mean in math?

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