Final answer:
To write an equation relating x and y, you can use the formula y = k/x, where k is the constant of variation. Given x = 2 and y = 4, the equation relating x and y is y = 8/x. When x = 4, y becomes 2.
Step-by-step explanation:
To write an equation relating x and y, we can use the formula y = k/x, where k is the constant of variation. Given that x = 2 and y = 4, we can plug these values into the formula to solve for k. 4 = k/2, so k = 8. Now, we can substitute k back into the formula to get the equation y = 8/x. To find y when x = 4, we can substitute x = 4 into the equation: y = 8/4, which simplifies to y = 2.