Please find the value of A,B,C&D

Given
A + B = 8
A + C = 13
B + D = 8
C - D = 6
Now
A + B = B + D
A = B + D -B
A = D
C - D = C - A
A + C = 13
C - A = 6
Adding 7 on both sides
C - A +7 = 6+7
C - A + 7 = A + C
C-C -A + 7 = A
-A +7 = A
7 = A+A
7/2 = A
A = 3.5
B = 4.5
C =9.5
D = 3.5
Answered by Gauthmath must click thanks and mark brainliest