Use the lengths of corresponding sides
so answer is 16:40 which simplifies to 2:5.
Add the 2 and 9 together:
2q+11
She posted 2/5 of them
90 times 2/5=180/5=36
she posted 36
90-36=54
she posted 2/3 of remaining (54)
2/3 times 54=108/3=36
54-36=18
she has not yet posted 18 of them
So we already drew two cards and both of them are spades. So that means there are 50 cards and 11 spades left.
Then third card being spades would be 11 / 50
Now there are 10 spades and 49 cards left.
So the probability for fourth card would be 10 / 49
Fifth card would be 9 / 48.
So the probability of next three cards being spades would be
Hope this helps.