How does knowing the double 6+6=12 solve the near double 6+7=13?

Because, if 6 + 6 = 12, then in 6 + 7, 7 can be splitted into 6 + 6 + 1, and so you find it easier...!!

left 3, up 4

step-by-step explanation:

just count the values of x & y of the vertex of the graph and see how many units in the x and y direction will get you from the f(x) graph to the f(x) graph