At what temperature (degrees fahrenheit) is the fahrenheit scale reading equal to (a) 6 times that of the celsius and (b) 1/5 times that of the celsius?

The relationship between temperature in degrees Fahrenheit, F, and degrees Celsius, C, is
F = 1.8C + 32

Part a.
If F = 6C, then
6C = 1.8C + 32
6C - 1.8C = 32
4.2C = 32
C = 7.62
Therefore, F = 6*7.62 = 45.71

45.7 °F (nearest tenth)

Part b.
When F = (1/5)C, then
0.2C = 1.8C + 32
0.2C - 1.8C = 32
-1.6C = 32
C = - 20
Therefore, F = 0.2*-20 = -4

-4 °F