A=B+2C , 3B = 2C +D ,A+2B = 2D How many B = D
A-2C = B (#1)
2C = 3B-D (#2), so
A-(3B-D) = B
A-3B+D = B
A+D = 4B
A = 2D-2B (#3). so
2D-2B+D = 4B
3D = 6B
D = 2B
2C = 3B-D (#2), so
A-(3B-D) = B
A-3B+D = B
A+D = 4B
A = 2D-2B (#3). so
2D-2B+D = 4B
3D = 6B
D = 2B