On Tuesday, 227 books were taken, so there are 235 - 227= <<235-227=8>>8 books left.
56 books were brought back on Thursday, so there are 8 + 56 = <<8+56=64>>64 books in the library.
Finally, 35 books are taken out on Friday, leaving 64 - 35 = <<29=29>>29 books available.
#### 29