To convert from Celcius to Kelvin just add 273
-30C + 273 = 243 Kelvin
10C + 273 = 283 Kelvin
50C + 273 = 323 Kelvin
To convert from Celcius to Fahrenheit is C * 1.8 +32
-30C * 1.8 + 32 = -22F
10C * 1.8 + 32 = 50F
50C * 1.8 + 32 = 122F
Hope that helps!