Answer:
26 units.
Step-by-step explanation:
AB + BC + AC = AC + AD + DC + 4
AC is common so
AB + BC = AD + DC + 4
AB + BC - AD - DC = 4
Substituting the given values
AB + 7 - 5 - 6 = 4
AB = 4 - 7 + 5 + 6 = 8
So the perimeter of ABCD
= AB + BC + AD + CD
= 8 + 7 + 5 + 6
= 26.