The denominator is greater than 1. So the value is less than $\int_0^{0.5}(1-2t)^3dt=\frac{1}{8}=\frac{16}{128}<\frac{16}{125}$.
The denominator is greater than 1. So the value is less than $\int_0^{0.5}(1-2t)^3dt=\frac{1}{8}=\frac{16}{128}<\frac{16}{125}$.