Use the point-slope form of a line given by: \(y-y1=m(x-x_1)\)

Let \((x_1,y_1)=(3,-4)\ and\ (x_2,y_2)=(7,0)\), the x-intercept so that the slope is: \(\displaystyle{m}=\frac{{{y}{2}-{y}{1}}}{{{x}{2}-{x}{1}}}=\frac{{{0}-{\left(-{4}\right)}}}{{{7}-{3}}}=\frac{{4}}{{4}}={1}\)

So, the equation is:

\(y-(-4)=1(x-3)\)

\(y+4=x-3\)

\(y=x-7\)