The ratio of ages of John and David is 3:4. Four years ago, the ratio of their ages was 2:3. How old is David now?
Question
The ratio of ages of John and David is 3:4.
Four years ago, the ratio of their ages was 2:3.
How old is David now?
Solution
Let's denote the current ages of John and David as 3x and 4x respectively.
Four years ago, John was 3x - 4 years old and David was 4x - 4 years old. According to the problem, the ratio of their ages at that time was 2:3.
So, we can set up the equation (3x - 4) / (4x - 4) = 2 / 3.
Cross-multiplying gives us 9x - 12 = 8x - 8.
Solving this equation for x gives us x = 4.
So, David is currently 4x = 4 * 4 = 16 years old.
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