Question

a+b=240
c+d=500
d-b+c=495
a-c=215
what is the value of d

Answer 1

c+d=500
                                        d= 500-c   
we knw tht,
                  d-b+c=495
so,  500-c -b+c =495
                     b=5
a+b=240
a=235

a-c=215
  c=20

d=500-20
    =480

Answer 2

C+D=500[GIVEN]
D= 500-C   
D-B+C=495
500-C -B+C =495[PUTTING THE VALUE OF D]
-B=495-500=-5
B=5
A+B=240[PUTTING THE VALUE OF B]
A+5=240
A=235.
A-C=215[PUTTING THE VALUE OF A]
235-C=215
-C=215-235=-20
C=20
C+D=500[PUTTING THE VALUE OF C]
20+D=500
D=500-20
D=480