Subtracting time

I'm working on a time tracking sheet. I have a weekly total column with the formula of =SUM(I4:I8). This entire column is formatted as [h]:mm. The current value is 31:49. I want to calculate how many hours until 40. Here are a couple of the things I have tried:

=TIME(40,0,0)-Table1[@Total]

=40-INT(Table1[@Total])

=40-Table1[@Total]

I finally got this to work with a static value: =TIME(40,0,0)-TIMEVALUE("31:49"), so then I tried these:

=TIME(40,0,0)-TIMEVALUE(""&Table1[@Total]&"")

=TIME(40,0,0)-TIMEVALUE(INDIRECT(Table1[@Total]))

I'm sure I'm missing something stupidly obvious, so what is it?