Ihave 3 children. their ages add up to 21, and when multiplied they equal 75. how old are they?

So represent the ages as x y and z with each being numbers

x+y+z=21
x times y times z=75
this is really tough for elementary school

one way is to find the factors of 75 or the numbers that add up to 75 and trial and error
use whole numbers becuase this is the world of math so

75=1 times 3 times 5 times 5
possible ages are
3,5,5
1,5,15
1,3,25
add them up

3+5+5=13
1+5+15=21 check
1+3+25=29

their ages are 1, 5 and 15