Hello : let A(-10,-3) B(7,14)
the slope is : (YB - YA)/(XB -XA)
(14+3)/17) = 1
an equation is : y=ax+b a is a slope
y = x +b
the line F through point B(7,14) : 14 =7+b
b = 7
the equation is : y =X+7
the x- intercept of F when y=0 : x+7 =0 so : x = - 7