Problem: the sum of ages of 5 children born at the intervals of 3 years each is 50 years . what is the age of the youngest child ?
Rationale: "explanation let the ages of children be x , ( x + 3 ) , ( x + 6 ) , ( x + 9 ) and ( x + 12 ) years . then , x + ( x + 3 ) + ( x + 6 ) + ( x + 9 ) + ( x + 12 ) = 50 5 x = 20 x = 4 . age of the youngest child = x = 4 years . answer a"
annotated_formula: subtract(subtract(divide(50, 5), 3), 3)