Answer:
180
Step-by-step explanation:
If 35% did not wear happy faces, then 100% -35% = 65% did wear happy faces.
Then we have ...
... 117 = 65% × (all children)
... 117/0.65 = all children = 180 . . . . . . divide by 65% = 65/100 = 0.65
There were 180 children in all.