Can someone me pls i would gladly appreciate it

Which of the following contains a variable?

Acd that is originally priced at $15.85 red-tagged for the sale. what is the sale price of the cd

1. ∠1 is complementary to ∠2 and ∠3 is complementary to ∠2. subtraction property of equality 2. m∠1 + m∠2 = 90 and m∠3 + m∠2 = 90 substitution 3. m∠1 + m∠2 = m∠3 + m∠2 definition of complementary 4. m∠1 = m∠3 given