Given:
- The relationship between x and y is given by the equation 3x + 4y = 20.
- The quartile deviation of x is 16.

To Find:
- The quartile deviation of y.

Explanation:
Step 1: Find the Mean of x and y.
- To calculate the mean of x, we rearrange the equation 3x + 4y = 20 to solve for x: x = (20 - 4y) / 3.
- We substitute this expression for x in the equation and solve for y: 3((20 - 4y) / 3) + 4y = 20.
- Simplifying the equation, we get 20 - 4y + 4y = 20, which is true for all values of y.
- This implies that x can take any value, and there is no unique mean value for x.
- Similarly, there is no unique mean value for y.

Step 2: Find the Deviation of x and y.
- The deviation of x from the mean can be calculated as: deviation of x = x - mean of x.
- Since there is no unique mean value for x, we cannot calculate the deviation of x.

Step 3: Find the Quartile Deviation of x and y.
- Quartile deviation is a measure of dispersion and is calculated as half the difference between the third quartile (Q3) and the first quartile (Q1).
- Since the deviation of x cannot be calculated, we cannot find the quartile deviation of x.

Conclusion:
- Since we cannot calculate the deviation or quartile deviation of x, we cannot determine the quartile deviation of y based on the given equation.
- Therefore, the quartile deviation of y cannot be determined.