A) x+5=13 -- subtract 5 from both sides
x=8
B) -6x=-30 -- they're both negative so change the sign to positive
6x=30 -- divide both sides by 6
x=5
C) x/4=18 -- multiply both sides by 4
x=72
D) x-2=-11 -- add 2 to both sides
x=-9
D gives the lowest answer.