I am going to assume that "v" is meant to be a "y"
the answer is b. (3)/(5x^6 y^6)
Answer: a) Length of wire to replace old one=9ft
b) Length of wire=3.09ft
Leftover wire=0.91ft
Step-by-step explanation: from the right angle triangle, Tan&=20/15
&=53.13°
Length of wire,x=cos 31.13=x/15
15cos31.13
X=9
b) Tan&=10/6
Tan^-110/6
&=59.05
Length= 6cos59.04
X=3.09
4-3.09=.91= leftover wire
(12 - 9) / 12 = (40 - x) / 40
3/12 = (40 - x) / 40
40(1/4) = 40 - x
10 = 40 - x
10 - 40 = -x
-30 = -x
30 = x <=== percent decrease from 40 to 30