First, isolate y on one side to find some information about the graph.
3x+4y=-10
4y=-10-3x
y=(-10-3x)/4
Now find out the x and y intercepts of this equation;
(0)=(-10-3x)/4
4x0=-10-3x
0=-10-3x
3x=-10
x=-10/3 or -3.3333 (x-intercept)
y=(-10-3(0))/4
4y=-10
y=-10/4 or -5/2 = -2.5 (y-intercept)
Plot these points onto your graph and connect the lines.
I have attached a graph below, I'm sorry I couldn't do it on paper.
Hope I helped :)