A business buys invoice forms at a cost of $4.45 a box for the first 20 boxes, $4.00 a box for the next 25 boxes, and $3.75 a box for any additional boxes. How many boxes of invoice forms can be bought for $234.00?
Let $x$ be the number of additional boxes of invoice forms bought.
The cost of the first 20 boxes is 20*$4.45 = $<<20*4.45=89.00>>89.00.
The cost of the next 25 boxes is 25*$4 = $<<25*4=100.00>>100.00.
The cost of the remaining boxes is $3.75*x.
So the total cost of all the boxes is $89 + $100 + $3.75*x = $234.
Therefore, $3.75*x = $234 - $189 = $45.
Therefore, x = $45 / $3.75 = 12.
Thus, the number of boxes of invoice forms that can be bought for $234.00 is 20 + 25 + 12 = <<20+25+12=57>>57. Answer: \boxed{57}.