Solving system of equations

1.x=3+y
x+4y=6

If a =6, what is the value of 2a(3b + 5c)?

What is the range for 31,39,29,34,37,24,36,33,34,28

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