How do you write an equation of a line given (7,-3), m=-4/7?

$y = - \frac{4}{7} \cdot x + 1$
Start with equation of a line $y = m x + b .$ Then sub in $x = 7 , y = - 3 \mathmr{and} m = - \frac{4}{7}$ into the equation; and solve for b.