Answer:
Correct choice is B
Step-by-step explanation:
Let a, b, c and d be the trapezoid's sides lengths.
The perimeter of the trapezoid is the sum of all sides lengths, thus,
If each side length is increased by a factor 7, then new sides have lengths 7a, 7b, 7c and 7d. The perimeter of new trapezoid is
Use the distributive property for this expression:
Since then