A mercury in glass thermometer reads 20 at the icepoint and 100 at steam point. Calculate the celsius temperature corresponding to 70 on the thermometer
g =mercury glass reading
c = celsius reading
c = m g + b
100 = m* 100 + b
0 = m * 20 + b
-------------------- subtract
100 = 80 m
m = 10/8 = 5/4
b = -20 m = - 25
so
c = 5/4 * 70 - 25 = 62.5