Answer:
Number of doubles games = 6
Number of singles games = 7
Step-by-step explanation:
Let the number doubles be d and number of singles be s.
There are 13 matches in progress.
             d + s = 13  ----------------------eqn 1
There are 38 people playing tennis. A doubles match requires 4 players, and a singles match requires 2 players.
          4 d + 2 s = 38  ----------------------eqn 2
eqn 1 x 2
             2d + 2s = 26  ----------------------eqn 3
eqn 2 - eqn 3
             4 d + 2 s -  2d + 2s = 38 - 26
               2d = 12
                d = 6
Substituting in eqn 1
              6 + s = 13     Â
                  s = 7
Number of doubles games = 6
Number of singles games = 7