In another universe temperature is measured differently than

In another universe, temperature is measured differently than here on Earth One scale is measured in degrees Frankenheit (F) and the other is measured in degrees Crazius (C). Suppose that the two scales are related by a linear equation C = aF + b. Use the fact that pure water freezes at 100 degree F and 30 degree C, and boils at -25 degree F and 90 degree C to find a and b

Solution

water freezes at

-100 F and 30 C

Relation between C and F is

C = aF + b

30 = -100*a + b

Similarly

90 = -25*a + b

Solving both equations:

subtracting 2 - 1 equation:

60 = 75*a

a = 4/5

which gives

b = 110