Question 969599
Let's start with 60 db

60=10 log(10^16x)
Divide both sides  by 10
6=log (10^16x)
raise each to the power of 10.  That removes the log.  Furthermore, 10 ^log x=x.  e^ln x=x.  They are opposites just like multiplication and division are.  Therefore, 10^{log 10^16x}=10^16x
10^6=10^16x

Divide by 10^16.

(10^6/10^16)=x 
x= 10^(-10)  because when you divide, you subtract exponents.  6-16=-10  
x=10^(-10) watts/sq meter.

For 85 decibels

85=10 log (10^16x)
Divide by 10
8.5=log (10^16x)

10^8.5=10^16x.  Don't try to get a specific number for 10^8.5 yet.  
Divide by 10^16, both sides

x=10^(-7.5)

Still don't get a specific number.  Leave it as is for now.

The louder is divided by the smaller, so we divide 10^(-7.5)/ 10^(-10)

Moving the negative exponent to the top makes it positive, so (-7.5+10)=2.5

The louder is 10^2.5 times louder than the smaller.  That answer is not unreasonable in that form, but most would want a specific ratio, not a power of 10. NOW you can raise 10^2.5 to get 316.2, which is how much louder 85 dB is than 60 dB.

Notice that decibels from 60 to 85 will be 10^[(85-60)/10] times louder.