If a thermometer indicates 30 degrees celsius, what is the temperature in degrees fahrenheit?
a. 24°f
b. 17°f
c. 54°f
d. 86°f

If a thermometer indicates 30 degrees Celsius, the temperature in degrees Fahrenheit is 86°F.

Boiling water measures 100 degrees in Celsius, and 212 degrees in Fahrenheit. Freezing water measure 0 degrees in Celsius, and 32 degrees in Fahrenheit. 

So, if you want to convert Celsius into Fahrenheit, you will need to:
Multiply by 180/100
Add 32

Let's convert 30 degrees Celsius into Fahrenheit.
30  180/100 = 54
54 + 32 = 86