Delta hedge- call option delta + put option delta =1

CFA Level II
#1

Call option delta + put option delta =1

Do we have this equation? See schweser use this equation to solve one question. Thanks.

#2

This is incorrect, the sum of the absolute values of the call and put deltas is one.

#3

Many thanks!

#4

Put delta = call delta – 1

Call delta – put delta = 1