Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What is the sum of the game with a PWin% of —, Term [c] of 1987–1988, and Win% less than 0.506?

### Inputs:
table_name: table, columns: ['Name [b ]', 'Term [c ]', 'Games', 'Win%', 'PWin%']

### Response:
SELECT SUM Games FROM table WHERE PWin% = — AND Term [c ] = 1987–1988 AND Win% < 0.506