Your question is incomplete, but I'll take a guess at what you're asking. In decimal form 85% = 0.85 and 30% = 0.30. 1/0.85 and 1/0.30 are the reciprocals.
Whole*Percent = Part
Example: What is 85% of 50?
The Whole is 50, the Percent is 85%. To find the Part:
50*0.85 = 42.5
Now suppose you know the part (42.5) and the percent (85%) and are asked to find the Whole.
Whole* Percent = Part
so
Whole = Part/Percent = Part*(Reciprocal of Percent)
Example: 42.5 is 85% of what number?
Whole = Part*(Reciprocal of Percent)
Whole = 42.5*(1/0.85) = 50
