If you formed an algebraic equation to model the sentence, "three times a number is equal to nine," how many variables would be in the equation? a. 1 b. 2 c. 3 d. 5

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