40y/72y^5

To simplify this expression, we can break down the terms and divide the coefficient (40) by the coefficient (72) and divide the variable (y) by the variable raised to the 5th power (y^5).

40y / 72y^5

First, simplify the coefficients:
40 / 72 = 5/9

Now simplify the variables:
y / y^5 = 1/y^4

Putting it all together:
(5/9) * (1/y^4) = 5 / 9y^4

Therefore, the simplified expression is 5 / 9y^4.