Question

The answer to the question below is 8/15 right?

Answer 1

This is below 8/15. It is around 1/15m

Answer 2

When you have something like this, to simplify the exponent you multiply them together, so the exponent is 1/3 x 1/5. 
1/3 x 1/5 is 1/15, so the simplified expression is: 
$m^{ \frac{1}{15} }$ 
Hope this helps!