a) \(40+13+\left(-30\right)+\left(-13\right)\)
\(=\left(13-13\right)+\left(40-30\right)\)
\(=10\)
b)
\(\left(-6\right)+\left(-660\right)+\left(-4\right)+660\\ \left(-6-4\right)+\left(660-660\right)\\ -10\)
c) \(\left(-217\right)+\left(-669\right)+217+702\)
\(=\left(217-217\right)+\left(702-669\right)\)
\(=33\)
d)
\(\left(-6\right)+\left(-660\right)+\left(-4\right)+660\\ \left(-6-4\right)+\left(660-660\right)\\ -10\)