When W is increased from 3 to 4, D is increased from 6 to 10, and L is increased from 8 to 12, G increases from 2700 to 6666.67. This is because the increase in W and D^2 is greater than the increase in L.
G varies directly as W and the square of D, and inversely as L. This means that G is proportional to the product of W and D^2, and inversely proportional to L.
When W=3, D=6, L=8 and G=2700, we can write the following equation:
G = k * W * D^2 / L
where k is the constant of proportionality.
Solving for k, we get:
k = G * L / (W * D^2) = 2700 * 8 / (3 * 6^2) = 100
Now we can use this value of k to find G when W=4, D=10, and L=12:
G = k * W * D^2 / L = 100 * 4 * 10^2 / 12 = 6666.67
Therefore, G is 6666.67 when W=4, D=10, and L=12.