Answer:
40 min
Step-by-step explanation:
his sister can do it twice as fast so the boy does 1 and the sister does 2. he will do 1/3 of the work and it will take 1/3 of the time
Answer:
3x+1.
Step-by-step explanation:
First we divide g(x)/f(x) (the process is in the first image):
5x-15 in Z7[x] is 5x-1 and
is
in Z7[x]. So
g(x)/f(x) = 
Now gcd(g,f) = gcm(f,r).
f(x)/r(x) = 
Then, gcd(f,r) = gcd(r,3x+1).
r/(3x+1) = 
Then, gcd(r, 3x+1) = gcd(3x+1,4) = 3x+1.
So, gcd(f,g) = 3x+1.