One cold night the temperature was 0 degrees at 8 p.m. The temperature dropped at a constant rate from 8 p.m. to midnight. At midnight the temperature was −16.8 degrees.
Let y be the temperature Let m be the rate of temperature drop in degrees per hour Let x be the number of hours elapsed since 8PM The initial temperature (at x = 0) is 0 y = mx Four hours from 8 PM, the temperature was -16.8 degrees -16.8 = m(4) m = -4.2 degrees per hour At 9PM, one hour will have elapsed. y = -4.2(1) y = -4.2 degrees
