1.   Solve n − 12 = 12 mentally.
    A. n = 24 B. n = 0
    C. n = 18 D. n = 12
    Hint

  2.   Solve 10 + r = 23 mentally.
    A. r = 33 B. r = 13
    C. r = 7 D. r = 3
    Hint

  3.   Solve p + 8 = 19 mentally.
    A. p = 7 B. p = 9
    C. p = 11 D. p = 27
    Hint

  4.   Solve n - 15 = 15 mentally.
    A. n = 0 B. n = 30
    C. n = 45 D. n = 15
    Hint

  5.   Choose the equation and solution that represents the sentence. A total of 21 points when 7 points are scored in the first half and n points are scored in the second half of a game.
    A. 7 − n = 21; 14 B. n − 21 = 7; 28
    C. n = 21 + 7; 28 D. 7 + n = 21; 14
    Hint