SAT Math Question of the Day

Math Category: Fractions Level 1:

Q: Simplify 13/39 + 12/42.

  1. 3/7
  2. 11/21
  3. 4/7
  4. 13/21
  5. 2/3

UNANSWERED.

The correct answer is D.

A: The answer is 13/21.

First, simplify:
13/39 + 12/42 = 1/3 + 2/7
The common denominator of 3 and 7 is 21.
1/3 + 2/7 = 7/21 + 6/21 = 13/21