Answer:
-40%
Step-by-step explanation:
NV = new value
OV = old value
percent change = (NV - OV)/(OV) × 100%
percent change = (30 - 50)/(50) × 100%
percent change = -20/50 × 100%
percent change = -40%
Answer:

Step-by-step explanation:
I used an online Fraction calculator to check my answer and I got 4/15 both times so you can trust this answer my friend.
Hope this helped you out.
Answer:
49
Step-by-step explanation:
side 1 = |18-3|= 15
side 2 = |12-3| = 9
side 3 = |16-4| = 12
side 4: 
perimeter = 15 + 9 + 12 + 13,4= 49,4 = 49
40% percent times 70 is want I believe