sam is 5 years older than his sister.Three years from now, the sum of their ages will be 21 how old is Sam now
Let's assume Sam's sister's age is x.
According to the problem, Sam is 5 years older than his sister, so Sam's age is x + 5.
Three years from now, Sam's sister will be x + 3 years old and Sam will be (x + 5) + 3 years old.
According to the problem, the sum of their ages three years from now will be 21: (x + 3) + ((x + 5) + 3) = 21.
Simplifying the equation, we get: 2x + 11 = 21.
Subtracting 11 from both sides: 2x = 10.
Dividing both sides by 2: x = 5.
So, Sam's sister is currently 5 years old.
Since Sam is 5 years older, Sam is currently 5 + 5 = 10 years old.
Therefore, Sam is currently 10 years old.