okay so all you are doing is filling out the char to do this you fine the increasing rate or the pattern. so 2*3=6 5*3=15 so the pattern is that you are multiplying every input by 3 so 0*3=0
1*3=3
3*3=9
4*3=12
then to fine the differences you just simply write how much you increased or decreased so every difference for this chart will be +3 hope this helped you have an amazing day!!!!