A+B+C+D=38*4=152;A+B=42*2=84B+C+D=36*3=108B=84+108-152=40
A+B+C+D=38*4=152;A+B=42*2=84B+C+D=36*3=108B=(A+B)-[(A+B+C+D)-(B+C+D)]=84-(152-108)=40
A = 38*4 - 36*3 = 44B = 42*2 - 44 = 40
42*2+36*3-38*4=84+108-152=40