The nth term of a sequence is 2n-1
The nth term of a different sequence is 3n+1
Work out the three numbers that are in both sequences and between 20 and 40

n1= 11, n2=12 n3=13

Step-by-step explanation:

an=2n-1

bn=3n+1

set an to 20 and ask yourself when is it going to be at least 20, of course smaller or same as 40 at the same time so

20≤2n-1≤40

the first n is 11, second one 12 and third one 13.