First find the total sentence length for the arson: 6 years/count * 2 counts = 12 years
Then find the total sentence length for the explosives: 12 years * 2 = <<12*2=24>>24 years
Then add each sentence to find the total sentence length: 12 years + 24 years + 20 years = <<12+24+20=56>>56 years
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