Let U = {3, 6, 9, 12, 15, 18, 21, 24} and A = {9, 12, 15, 21}. A'

A¹ = { 3 , 6, 18 , 24}

Step-by-step explanation:

Explanation:-

Universal set

If all the sets under consideration are the subsets of a fixed set 'U' then the set 'U' is called the Universal set.

Given  U = {3, 6, 9, 12, 15, 18, 21, 24}

Given A = {9, 12, 15, 21}

Compliment Of A

The Complement of a set A is all the objects that do not belong to set A

The Compliment of A is denoted by A¹

A¹ = U - A

     = {3, 6, 9, 12, 15, 18, 21, 24} - {9, 12, 15, 21}

A¹ = { 3 , 6, 18 , 24}

an altitude of 15,000 feet

step-by-step explanation:

b

step-by-step explanation:

a difference is the result of subtraction. while each of these expressions has subtraction in it, a difference will be the result when subtraction is the last operation applied in the order of operations for the expression. this means subtraction must be outside of the parenthesis. only b has this.