Draw the graphs of linear equations $y=x$ and $y=-x$ on the same cartesian plane.

What do you observe?

$x=5, y=2$ is a solution of the linear equation

The linear equation that converts Fahrenheit $(F)$ to Celsius $(C)$ is given by the relation

$C =\frac{5 F -160}{9}$

$(i)$ If the temperature is $86^{\circ} F$, what is the temperature in Celsius?

$(ii)$ If the temperature is $35^{\circ} C ,$ what is the temperature in Fahrenheit?

$(iii)$ If the temperature is $0^{\circ} C$ what is the temperature in Fahrenheit and if the temperature is $0^{\circ} F$, what is the temperature in Celsius?

$(iv)$ What is the numerical value of the temperature which is same in both the scales?

For what value of $c,$ the linear equation $2 x+c y=8$ has equal values of $x$ and $y$ for its solution.

Determine which of the given equations is represented by the graph given in the figure below