Last month Brad read thrice 6 books for a total of 3*6 = <<3*6=18>>18 books
This month Williams read twice 8 books for a total of 2*8 = <<2*8=16>>16 books
Across the 2 months Brad has read 18+8 = <<18+8=26>>26 books
Across the 2 months William has read 6+16 = <<6+16=22>>22 books
Brad has read 26-22 = <<26-22=4>>4 more books
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