Question

A={x€N/5x:3} și B={x+1suprax+2/x€A}

Answer 1

A={0, 5/3, 10/3, 15/3, 20/3......}
A={5k/3 |k∈N}
(x+1)/(x+2)=(5k/3+1)/(5k/3+2)=(5k+3)/3:(5k+6)/3=(5k+3)/3·3/(5k+6)=
=(5k+3)/(5k+6)
B={3/6, 8/11, 13/16.....}
B={(5k+3)/(5k+6) | k∈N}