Thanks a lot Matt for your time. I found the answer thank to you.
classdef ModelBrick
properties
B=1
C=20
end
properties(Dependent = true)
A=1
end % end of dependent properties
methods
function obj= set.A(obj,a)
obj.B=a/obj.C
end
function a= get.A(obj)
a=obj.B*obj.C;
end
end
end