If the point $(2,3)$ lies on the graph of the equation $3 x+a y=18,$ find the value of $a$.

Express the following linear equation in the form $a x+b y+c=0$ and indicate the values of $a, b$ and $c$ in each case

$x=\frac{2}{5} y+10$

Write four solutions for each of the following equations

$3 x+y=11$

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?

If $(k, 3)$ is a solution of the equation $2 x+5 y=17,$ find the value of $k$