AB is congruent to side DE.
So,
AB= 23 and DE= 23
I hope this helps!
~kaikers
ANSWER
The percentage decrease is 10.4%.
EXPLANATION
To calculate percentage decrease, use the formula,
Percentage decrease

Yesterday the price of coffee was 2.40. This is the old price.
Today the price is 2.15. This is the new price.




To the nearest tenth, we have:

Therefore the percentage decrease is 10.4%.
Assuming your solving for y:
py+7=6y+q
-6y -7 -6y -7
(p-6)y = q-7
divide both sides by p-6
y=(q-7)/(p-6)
To figure out the slope you would want to use this formula for 2 of the points: Y2-Y1/X2-X1.
if you followed this for (-3,-2) and (3,2), you would get 2-(-2)/3-(-3)
this would equal 4/6, which simplifies to 2/3
the slope of line p = 2/3x