Dave is three times older than Jim, and Jim is half Bill's age. If their average age is 64, what is Jim's age?

Dave is 96 years old. Jim is 32 years old. Bill is 64 years old.

d = 3j

j = 1/2b

64 = (d + j + b) / 3

d = 3 (1/2b)

d = 1.5b

64 = (1.5b + 1/2b + b) / 3

Combine like terms.

64 = (3b) / 3

Multiply both sides by 3.

192 = 3b

Divide both sides by 3.

64 = b

Because we have the value for b we can plug it into the other equations to solve for the other ages.

j = 1/2b

j = 1/2 (64)

j = 32

d = 3j

d = 3 (32)

d = 96