jmc

Since the side lengths of $△DEF$ are $50\%$ larger than the side lengths of $△ABC$, then these new side lengths are $\frac{3}{2}(6)=9$, $\frac{3}{2}(8)=12$, and $\frac{3}{2}(10)=15$.

We know that $△DEF$ is right-angled, and this right angle must occur between the sides of length 9 and 12 (since it is opposite the longest side). Therefore, the area of $△DEF$ is $$\frac{1}{2}(9)(12)=\boxed{54}.$$