Answer:
5) because ABCD is a rectangle => AC = BD
<=> 4x - 5 = 3x - 1
<=> 4x - 3x = -1 + 5
<=> x = 4
6) because EFGH is a rhombus
=> HF is the bisector of the angle EHG
=> EHF = GHF
<=> 3x - 15 = 2x + 9
<=> x = 24
