Answer:
For A: The linear equation is

For B: The temperature of normal body in degree Celsius is 37° C.
Step-by-step explanation:
Linear equations are defined as the equations in which the highest power of a variable is '1'. The general equation for a linear equation is:

where,
y = Y-coordinate
m = slope of the line
x = X - coordinate
c = intercept on y-axis
For the given equation:

The linear equation representation for the given equation is:

We are given a value of temperature in degree Fahrenheit. To calculate its value in degree Celsius, we use the equation above.
Putting value of F = 98.6 in above equation, we get:

Hence, the temperature of normal body in degree Celsius is 37° C.