Answer:
(a)

(b)The boiling point of water in Celsius scale is 100°C.
(c)The setting in Celsius scale is 26.7°C.
Explanation:
Given that,the formula is
......(1)
(a)
Given that,

[ subtracting 32 from both sides]


......(2) [Multiplying
]

(b)
Given that, the boiling point of water is 212°F.
Putting F=212 in equation (2)




The boiling point of water is 100°C.
(c)
Given that, a house thermostat is set at 80 degree.
Putting F=80 in equation (2)



The setting in Celsius scale is 26.7°C.