155095

Firstly I cut out all of the squares.
Secondly I worked out that the area of all of the shapes adds up to 1056cm squared.
Then I calculated that 33 x 32 = 1056. So one side of the rectangle must be 33cm and the other 32cm.
The 18cm square and 15cm square add up to 33cm.
The 18cm square and 14cm square add up to 32cm.
So the 18cm and 15cm square must make up the bottom half of the rectangle and the 18cm and 14cm square make up the left hand side.
I then fit all of the remaining shapes into the rest of the rectangle area (see attached photo).