Six subtracted from 54 is 48
54 subtracted by 49 = 5
54
67
-46
6
8n - (-54/9) = -188n - (-6) = -188n + 6 = -184n + 3 = -94n + 3 - 3 = -9 - 34n = -124n/4 = -12/4n = -3
0
54 is the mudaine answer, but it's 42 in base 13 math (see the Hitchhiker's Guide).
6
12
-6
54