Hey there!
To find how many kids went swimming given that there were 25 kids in total and 40% of them went swimming, you must multiply the percent by the whole:
40%*25
Before you do this, first convert the percent to a decimal:
40%=0.40
Now, multiply your expression:
0.40*25
0.40*25=10
Therefore, your final answer would be that 10 out of the total 25 kids went swimming.
Hope this helps and have a nice day! :)