I’m not sure...but I think
x+y=5
If x =15
Then 15+y=5
Y= 10
The 2nd robot can do the task in 10min
X(x-1)(x^2+4)=(x^2-x)(x^2+4)=(x^4)+(4x^2)-(x^3)-(4x)=(x^4)-x(x^2+4)+(4x^2)
Lack of prey
Hope this helped.
An=a1+d(n-1)
a1=first term
d=common difference
n=which term
common difference is 5 first term is 2
an=5+2(n-1)
19th term is n=19
a19=5+2(19-1)
a19=5+2(18)
a19=5+36
a19=41
19th term is 41
