If the exponent is a negative number, then you make it a fraction, with the exponent on top as a positive and the coefficient as a positive on the bottom AFTER you multiply, so what happens is if the coefficient has a negative exponent, you multiply the number by the exponent, make it positive, and put it under 1 as a fraction. So your answers are:
1/7
1/125
1/36
Hope this helps! Stay safe out there :)