Help I don’t get this

:24% of students in a class are girls. if there are less than 30 students in this class, how many students are there? how many girls are there?

Avery’s piggy bank has 300 nickels, 450 pennies, and 150 dimes. she randomly picks three coins. each time she picks a coin, she makes a note of it and puts it back into the piggy bank before picking the next coin.

When 60% of a number is added to the number the result is 192 what is the bumber