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
8 is the greatest common factor
Answer: An equations is a number, a variable, or a combination of numbers and variables and operational symbols. An equation is made up of two expressions connected by an equal sign.
Example Expression: 8x+5y-3x-5
Example Equation: 5x-4=x
Hope this helps a little bit:)