What is the slope of a line that passes through (-4,-13) and (19,11)

The slope of the line is the gradient, which you can find through rise over run

m (gradient) = (y1 - y2) / (x1 - x2)

where (x1, y1) is the coordinate of the first point, and (x2, x2) is the coordinate of the second point

in your question: 
x1 = -4
x2 = 19
y1 = -13
y2 = 11

m = (-13 -11) / (-4 -19) = -24 / -23 = 24/23 or 1.04 (2d.p.)

hope that helps :)