[ p+9 ]= 11
pretend that there is a +1 in front of the bracket
1 [ p+9 ]= 11
multiply the bracket by 1
(1)(p)=p
(1)(9)=9
p+9=11
move +9 to the other side
sign changes from +9 to -9
need to get p by itself
p+9-9=11-9
p=11-9
answer:
p=2
