diff --git a/Lesson15/Lesson15.odp b/Lesson15/Lesson15.odp
index 52ca6a9..ff4364b 100644
Binary files a/Lesson15/Lesson15.odp and b/Lesson15/Lesson15.odp differ
diff --git a/Lesson15/Lesson15.pdf b/Lesson15/Lesson15.pdf
index cf7a22f..1626473 100644
Binary files a/Lesson15/Lesson15.pdf and b/Lesson15/Lesson15.pdf differ
diff --git a/Lesson17/Lesson17.odp b/Lesson17/Lesson17.odp
index e9d52b1..a64838a 100644
Binary files a/Lesson17/Lesson17.odp and b/Lesson17/Lesson17.odp differ
diff --git a/Lesson17/Lesson17.pdf b/Lesson17/Lesson17.pdf
index 1ea9c0c..e2d82f0 100644
Binary files a/Lesson17/Lesson17.pdf and b/Lesson17/Lesson17.pdf differ
diff --git a/Lesson18/Lesson18.odp b/Lesson18/Lesson18.odp
index 6f7e1d3..35e2a02 100644
Binary files a/Lesson18/Lesson18.odp and b/Lesson18/Lesson18.odp differ
diff --git a/Lesson18/Lesson18.pdf b/Lesson18/Lesson18.pdf
index a0db5a2..bce9831 100644
Binary files a/Lesson18/Lesson18.pdf and b/Lesson18/Lesson18.pdf differ
diff --git a/Lesson19/Lesson19.odp b/Lesson19/Lesson19.odp
index 0c89cbd..ac42082 100644
Binary files a/Lesson19/Lesson19.odp and b/Lesson19/Lesson19.odp differ
diff --git a/Lesson19/Lesson19.pdf b/Lesson19/Lesson19.pdf
index c9ca94c..b5c1f50 100644
Binary files a/Lesson19/Lesson19.pdf and b/Lesson19/Lesson19.pdf differ