Question 789149
{{{1.8=9/5}}}
The multiplicative inverse is {{{1/((9/5))=1(5/9)=5/9}}}
There is no way to write that as an exact decimal.
 
If you are trying to convert degrees Farenheit to Celsius, you can easily use the fraction.
The scales meet at {{{-40^o}}} and you can use other reference points like the freezing point of water, which is {{{32^o}}}{{{F}}} anf {{{0^o}}}{{{C}}}
 
If yout temperature is {{{104^o}}}{{{F}}}, that is
{{{104^o}}}{{{F-32^o}}}{{{F=72^o}}}{{{F}}}  above freezing
To get to degrees Celsius multiply times {{{5/9}}} which means multiply times 5 and divide by 9, or divide by 9 first and then multiply times 5.
Either way {{{72*(5/9)=40}}}, so {{{104^o}}}{{{F=40^o}}}{{{C}}}