Question 169688
I will show you 2 problems 1 and 4 and then you should get the pattern of how its done, remembering that consecutive intergers with a given variable a is a,a+1,a+2 etc., whereas consecutive odd or even intergers would be written as a,a+2,a+4 etc. with that background.

1.) lets call our 4 consecutive integers a,a+1,a+2,a+3
:
2 times the smallest which is a=2a....12 more than largest(a+3) is (a+3)+12
:
2a=(a+3)+12 subtract a from each side
{{{highlight(a=15)}}} so our integers are 15,16,17,18
:
4.) Lets call our 3 consecutive even integers a, a+2,a+4
sum of the smallest(a) plus  twice the second(2(a+2)) equals 20 more than the 3rd((a+4)+20)
:
2a+2(a+2)=(a+4)+20
3a+4=a+24---->subtract a and -4 from both sides
2a=20
{{{highlight(a=10)}}} so our even integers are 10,12,14