We'll let x= Sara's age, since everything is defined in terms of her age.
Jamil's age= 5x.
Donald's age = 5x * (3/5) which = 3x.
Then we add all those together, x+5x+3x, ending up with 9x in total.
Then we say 9x=36, the total of their ages.
divide both sides of the equation by 9, ending up with x=4.
Sara is 4 years old, Jamil is 5 times older, so 5*4 which is 20.
Donald is 20 * (3/5) which is 12.
If we add those all up to check our answer, they should come to 36.