Let's find 2 decipherable points on the graph. 
1. (0, 4) 
2. (4, 0) 
Now, solve for slope.
Slope formula: 

Plug in and solve: 

Slope: 

Finally, plug into point-slope formula and solve for slope-intercept.
Point-slope formula: 

 where m = slope
Plug in and solve for slope-intercept.

Answer: 
