9.1 problem 241
  9.2 problem 242
  9.3 problem 243
  9.4 problem 244
  9.5 problem 245
  9.6 problem 246
  9.7 problem 247
  9.8 problem 248
  9.9 problem 249
  9.10 problem 250
  9.11 problem 251
  9.12 problem 252
  9.13 problem 253
  9.14 problem 254
  9.15 problem 255
  9.16 problem 256
  9.17 problem 257
  9.18 problem 258
  9.19 problem 259
  9.20 problem 260
  9.21 problem 261
  9.22 problem 262
  9.23 problem 263
  9.24 problem 264
  9.25 problem 265
  9.26 problem 266