\text { (c) Compute the summation. } \sum_{k=1}^{5}(-1)^{k}\left(2^{k}+3\right)=\ldots \ldots \ldots \ldots (d) The negation for the statement "Vn E Z, if n is divisible by 21, then n is divisibleby 3 and n is divisible by 7" is (e) The contrapositive for the statement "a is even if a is divisible by 6" is
Fig: 1
Fig: 2
Fig: 3
Fig: 4
Fig: 5
Fig: 6