Sarah can use a linear equation to show the relationship between temperature and time.
The general form of a linear equation is y = mx + b, where x is the independent variable (in this case, time) and y is the dependent variable (in this case, temperature). The slope of the line is represented by m, and the y-intercept is represented by b.
In this case, we know that the temperature started at 1 degree and rose 2 degrees every 3 hours. This means that the slope of the line is 2/3, and the y-intercept is 1.
Therefore, the equation that Sarah can use to show this information is:
y = (2/3)x + 1
where y is the temperature in degrees, and x is the time in hours.