We first expand out the (ax)2 on the top of the second fraction to give a2x2.
Also, because it is multiplication, we can write it as one fraction (multiply tops, multiply bottoms).
`(18sy^3)/(ax^2)xx((ax)^2)/(3s) = (18sy^3xxa^2x^2)/(ax^2xx3s)`
Next, we cancel the 18 on top with the 3 on bottom (giving 6 on top).
Also we can cancel the s on top and bottom.
The a2 on top cancels with the a on bottom to give a on top.
The x2 on top cancels with the x2 on bottom to give 1.
We then multiply out what is left to give the final answer.