I'm stuck on a practice problem that seems so easy but I'm drawing a blank. I need to explain what the "student" was doing and why in steps 1&2. I need to figure out a computation to complete the problem using the method the "student" is using.

67+86

step 1: 7x2=14

14-1=13

step 2: 6+8=4+10= 14 so 60+80=140

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