So Henry pulled out a total of 7 tiles (3 consonant tiles and 4 vowel times). You take that 7 and divide the total number of tiles, 35 by it.
35/7
=5
This gives you 5
You then take that 5 and multiply it by the amount of consonant vowels he pulled out, which is 3.
5x3
=15
So your answer is...
D.) 15 Tiles
I hope this helped! : )