A line is described by the equation $y-4=4(x-8)$. What is the sum of its $x$-intercept and $y$-intercept?
I know that the $x$-intercept is the value of $x$ when $y=0$, and the $y$-intercept is the value of $y$ when $x=0$. To find the $x$-intercept, I can plug in $y=0$ into the equation and solve for $x$. So I get $0-4=4(x-8)$, which simplifies to $-4=4x-32$, and then to $4x=28$, and then to $x=7$. So the $x$-intercept is 7. To find the $y$-intercept, I can plug in $x=0$ into the equation and solve for $y$. So I get $y-4=4(0-8)$, which simplifies to $y-4=-32$, and then to $y=-28$. So the $y$-intercept is -28. To find the sum of the $x$-intercept and the $y$-intercept, I just need to add 7 and -28. So I get 7 + (-28) = -21. 