1.   Find the missing number in the equation.

__ + 10 = 10 + 15

    A. 15 B. 25
    C. 10 D. 5
    Hint

  2.   Find the missing number in the equation.

__ + 19 = 20 + 11 + 19

    A. 19 B. 11
    C. 31 D. 20
    Hint

  3.   Find the missing number in the equation.

13 + 12 = 5 + 8 + __

    A. 10 B. 13
    C. 4 D. 12
    Hint

  4.   Find the missing number in the equation.

10 + 6 + 4 = 8 + 8 + __

    A. 4 B. 6
    C. 20 D. 7
    Hint

  5.   Find the missing number in the equation.

8 + 5 + 7 = 8 + 7 + __

    A. 5 B. 6
    C. 7 D. 15
    Hint