Barney is y years old. His brother is 3 times as old as he is. His sister 5 years younger than his brother. a. Find his brother's age in terms of y. b. Find his

Barney = y years old

a) His brother's age in terms of y:
His brother is 3 times as old as Barney's.
His brother = 3 × Barney's age
His brother = 3 × y
His brother's age = 3y

b) His sister's age in terms of y
His sister is 5 years younger than his brother.
His sister = his brother's age - 5
His sister's age = 3y - 5

c) If y = 3, how old his sister?
His sister's age = 3y - 5
His sister's age = 3 × 3 - 5
                         = 9 - 5
                         = 4
His sister is 4 years old