Read the rules
6-3-1=2, 6+3-1=8, Merge both results=28
8-4-1=3, 8+4-1=11, Merge both results=311
10-5-1=4, 10+5-1=14,Merge both results= 414
12-6-1=5, 12+6-1=17,Merge both results= 517
Done.