it has 40 students given that 75 of a mathematics test calculate the number of students who failed the test

In the following diagram it is given that dec, ab || dc, ad || eb, and ad is congruent to bc. a)why isn't abc a parallelogram even though it has a pair of parallel sides and a pair of congruent sides b)explain why be must be congruent to bc. further explain what type of triangle this makes triangle abc and what it tells you about angle 1 and angle 2c) finally why must angle 3 be congruent to angle 1? further, explain why we know that angle 3 is congruent to angle 2

Ineed the answers for this one as well!

If there are 825 students at cherry hill high school and 4 out of every 5 students voted in the student council election, how many students voted?