What does d equal when r = 1/2 (c - d)?

r = 1/2 (c - d)
2r=c-d
d=c-2r answer//

checking

r=1/2(c-(c-2r))
r=1/2(c-c+2r)
r=1/2(2r)
r=r correct!

r = 1/2(c - d)
c - d = 2r
d = c - 2r

2 r = c - d

d = c - 2 r

om

need more information pls.

Since d is 2r, and r is 1/2(c-d)

d = 2{1/2(c-d)} = cd

d = c-2r