Statements Reasons 1. EG = FH 1. Given 2. EG = EF + FG 2. [1] SEGMENT ADDITION POSTULATE 3. FH = FG + GH 3. Segment Addition 4. EF + FG = FG + GH 4. [2] ADDITION PROPERTY OF EQUALITY5. EF = GH 5. Subtraction Property of Equality Your reason for 4 is wrong. The left side of statement 4, EF + FG, is equal to EG (from statement 2). The right side of statement 4, FG + GH, is equal to FH (from statement 3). EG and FH are equal things (from statement 1). So EF + FG and FG + GH, respectively, are equal to equal things EG and FH, respectively. So the postulate to give for 4 is magnitudes equal to equal magnitudes are equal to each other Justification: https://archive.org/stream/planegeometry00duregoog/planegeometry00duregoog_djvu.txt https://books.google.com/books?id=-i4AAAAAYAAJ&pg=PA26&lpg=PA26&dq=%22magnitudes+equal+to+equal+magnitudes+are+equal+to+each+other%22&source=bl&ots=b9rctac0iC&sig=ACfU3U0rvS7BnM8FWVV7vgt7-BbN_0dFGw&hl=en&sa=X&ved=2ahUKEwion67hqpb0AhUMTDABHdXMC6UQ6AF6BAgDEAM#v=onepage&q=%22magnitudes%20equal%20to%20equal%20magnitudes%20are%20equal%20to%20each%20other%22&f=false Edwin