CREATE TABLE table_29703 ("Model" TEXT, "PPI  ( pixels per inch  ) " FLOAT, "ppcm  ( pixels per cm  ) " FLOAT, "Resolution" TEXT, "Typical viewing distance  ( in/cm ) " TEXT, "Pixels per degree  ( PPD ) " FLOAT)

How many different PPI does the model with ppcm of 87 have?
SELECT COUNT("PPI (pixels per inch )") FROM table_29703 WHERE "ppcm (pixels per cm )" = '87'
SELECT COUNT("PPI (pixels per inch )") FROM "table_29703" WHERE "ppcm (pixels per cm )" = '87'