The standard linear equation is y=ax+b, where a is the slope=-4/5 and b is the y intercept, to be found. So we have so far y=-4/5x+b. The line passes through (-7,0) so x=-7 and y=0 can be substituted: 0=28/5+b, and b=-28/5. The full equation is y=-4/5x-28/5. This can be made to look a little tidier: 5y+4x+28=0.