Question

If the point $A(4,1)$ lies on the graph of the equation $5x+ay=19$, then find $a$.

Answer 1

Point $A(4,1)$ lies on the graph of the equation
$5x+ay=19$
It satisfies the equation.
$\therefore$ Substituting $x=4$ and $y=1$ in the above equation, we get
$5\left(4\right)+a\left(1\right)=19$
$20+a=19$
$a=19-20$
$a=-1$