This question is about what happens to the value of y when the value of x is doubled in different equations.
For the equation y = 8x, what happens to the value of y when x is doubled?

We are testing the effect of doubling x on the equation y = 8x. Let's pick a starting value for x, for example, x = 10. The original y would be y = 8 * 10 = 80. Now, let's double x. The new x is 2 * 10 = 20. The new y will be y = 8 * 20 = 160. Comparing the new y (160) to the original y (80), we see that 160 = 2 * 80. The value of y has doubled. Algebraically: Original: y = 8x New x: x_new = 2x New y: y_new = 8(x_new) = 8(2x) = 16x. Since the original y was 8x, the new y (16x) is 2 * (8x), which is double the original y.