Answer:
Your full equation is then y = -3*x + 80.
Explanation:
This sounds like a linear equation that can be put in "y = m*x + b" form because there is a constant Y-intercept value ("b," the starting point) and a constant slope ("m," the rate of change).
The trick here is to pick out these values from the word problem. The first thing to look for are key words like "starting at," "at time 0," or "when x = 0." These describe when the line crosses the Y axis (which is where x = 0). This number is also the "b" from the equation for a line: y = m*x + b. Your problem contains the phrase "starting at 80 degrees Fahrenheit," so our Y-intercept is b = 80 degrees Fahrenheit.
The next thing to look for is the slope, m. The slope of the line explains how fast it changes. A very big (or very negative) value of m means a steeper line; a value of m closer to zero means a line that looks more horizontal (i.e. it doesn't change very fast). In your problem, the temperature "dropped 3 degrees per minute." Because the temperature is getting lower as time passes, the slope of the line will be negative. So, m = -3 degrees Fahrenheit per minute.