Which expression is equivalent to 27 + 15?

Question

A. 3(24 + 12)
B. 3(9 + 5)
C. 9(3 + 15)
D. 9(18 + 6)

3(24 + 12) 3(9 + 5) 9(3 + 15) 9(18 + 6)

Answer 1

A. 3(24 + 12) = 3(24) + 3(12) = 72 + 36
B. 3(9 + 5) = 3(9) + 3(5) = 27 + 15
C. 9(3 + 15) = 9(3) + 9(15) = 27 + 135
D. 9(18 + 6) = 9(18) + 9(6) = 162 + 54

Answer 2

You may answer this multiple-choice question in either of two ways:

 (1) distribute the distractors [that is, the possible answers] and compare to the problem to find the key [that is, the correct answer]

 (2) factor the coefficient in each distractor from the problem expression to see if it now matches

 

Kendra F. did (1); let's do (2) [it is only two computations since only 3 and 9 are factors in distractors:

   27 + 15  = 3 ( 9 + 5 )

   27 + 15  = 9 ( 3 + non-integer )

 

We got the answer accurately and pretty quickly !     [this is important on standardized tests]