Let Tony's age = x
He is 4 years younger than his brother Josh, so Josh's age would be x + 4
He is 2 years older than his sister, so her age would be x - 2
He has a twin, which would be the same age, so the twins age is also x
They all add together to equal 66, so you get:
x + x + x+4 + x-2 = 66
Simplify:
4x +2 = 66
Subtract 2 from both sides:
4x = 64
Divide both sides by 4:
x = 64/4 = 16
Tony is 16 years old.
