How can i find the slope for the roof ?

Slope is the rise over the run. In other words, the difference in y values divided by the difference in x values. Start at the bottom corner of the roof and count the tiles upwards until you get to the top tip of the roof. It should be 4. Now from that point, count over to the right until you are at the top. It should be 5.

So the slope is 4/5 or 0.8.

6/ 11 = 0.545454 so your answer is55%