There were 75 cards in all.
Emily: 2/5 of 75 = 2/5 * 75 = 30
Emily signed 30 cards, and left 75 - 30 = 45
Josh: 1/9 * 45 = 45/9 = 5
Josh signed 5 cards and left 45 - 5 = 40
Tatiana: 20% * 40 = 0.2 * 40 = 8
Tatiana signed 8 cards and left 40 - 8 = 32
Answer: There are 32 cards left to sign.