Answer:
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Well you only do that when you are in the ones place and you have to regroup a 1in the tens place if you go past 19 then you are going to have to regroup a 2
Y=3x
explain
4x3=12 , 5x3=15 , 6x3=18 ,.......
Can you explain it more clear because my english is not very good, I want to easy to help you
Here is the graph! I hope this helps!