Dave is d years old. Tracy is twice Dave's age. What is the SUM of Dave and Tracy's ages, in terms of d ?

Dave is d years old. Tracy is twice Dave's age. What is the SUM of Dave and Tracy's ages, in terms of d ?

• A. 3d
• B. 2d
• C. 4d
• D. d+3

Answer: (A)

The main idea is to express both ages in terms of the same variable and then add them. Dave’s age is given as d. Tracy is twice Dave’s age, so Tracy’s age is 2d. The sum of their ages is d + 2d, which equals 3d. For example, if d = 10, Dave is 10 and Tracy is 20, and the total is 30, which is 3 × 10. So the sum, in terms of d, is 3d.

The main idea is to express both ages in terms of the same variable and then add them.

Dave’s age is given as d. Tracy is twice Dave’s age, so Tracy’s age is 2d. The sum of their ages is d + 2d, which equals 3d. For example, if d = 10, Dave is 10 and Tracy is 20, and the total is 30, which is 3 × 10.

So the sum, in terms of d, is 3d.