Answer:
Step-by-step explanation:
I think it is a ratio problem since the sides and trapezoid are congruent
It appears to be simplier than I thought. Each NEW base decreases EVERY equal step up by the SAME amount
The difference between the the bottom base and middle base is 3.5
21 - 17.5 = 3.5
The difference between the middle base and the top base is the same 3.5 so
17.5 - 3.5 = 14 is the length of the top base 3x + 2
so 3x + 2 = 14
3x = 14 - 2
3x = 12
x = 4 FINAL ANSWER
