At what temperature is the Fahrenheit scale reading equal to
(a) twice (b) half of Celsius ?

Explanation

As `t_(F) = (9)/(5)t_(C) + 32` and `t_(F) = (1)/(2)t_(C)`,
`(1)/(2)t_(c) = (9)/(5)t_(C) + 32` or `t_(C) = -(320)/(13) = -24.6^(@)C`