1.   Find the missing number in the equation.

18 + 8 = 8 + __

    A. 10 B. 18
    C. 8 D. 12
    Hint
  2.   Find the missing number in the equation.

__ + 10 = 10 + 15
    A. 5 B. 25
    C. 10 D. 15
    Hint
  3.   Find the missing number in the equation.

22 + 8 = 10 + 12 + __
    A. 10 B. 8
    C. 12 D. 22
    Hint
  4.   Find the missing number in the equation.

13 + 12 = 5 + 8 + __

    A. 10 B. 4
    C. 13 D. 12
    Hint
  5.   Find the missing number in the equation.

10 + 6 + 4 = 8 + 8 + __
    A. 20 B. 4
    C. 7 D. 6
    Hint