I have these two equations:
D0 - dp
S0 + sp
find value p, such that supply and demand is equal.
My assumption is to set p - p = 0, so that the equation is
D0 - dp - S0 + sp = 0
I solve to get
p = D0 - S0/ d - s,
but the answer in the book is
p = D0 - S0/ s + d,
I am not able to understand how they got this answer.