Question

PLEASE HELP ILL GIVE 5* AND THANKS.

Answer 1

Ok so a) is integers
And b) is 21

Explaining for B
From 1-3 he added 2
From 3-6 he added 3
From 6-10 he added 4
From 10-15 he added 5
So we r gonna continue the sequence by adding 6
15-21 we added 6