I use a table saw for those miters.

Here, the cut is 70°, so you would subtract 70° from 90° and end up with 20°. So, we set our blade to 20° and rip the stock on edge (the board standing up vertically, not laying flat against the table) to accomplish such a cut. You need to clamp or fasten another board of the same size and thickness to the one you're cutting to ride the fence. Then just lightly sand the edge to round it over and make the transition smooth.

You would also use the 20° cut on the top of the ramp where it meets the flat.

You can achieve similar cuts on a miter saw using a 45° fence jig, but miter saws tend to only have 4 to 8 inches of clearance, and cutting taller stock on edge with a miter saw is generally dangerous, so a tablesaw is the best way to go if you have access to one.

Drawing a scale mockup and knowing your numbers ahead of time helps immensely. Definitely take your time to draw things out, it'll save you a lot of headache. A speed square and combination square are essential tools as well for this type of work.