Answer:
A. How can the equation be used in temperature conversion?
You take the conversion equation C = (5/9) (F - 32) and you replace the F by the value of Fahrenheit degrees... then solve the calculations to get the degrees in Celsius.
For example, if you have 80°F to convert in °C:
C = (5/9) (80 - 32) = (5/9) (48) = 26.66 °C
B. How can you use the graph to find the body temp in C?
Using the graph will give a very imprecise measure due the scale of the graph.
But you would have to find 98.6 on the axis of X (it represents the °F), then go upwards until you find the line....
Then report that position on the line on the Y-axis (representing the °C) to get your measure.