Well this is just a triangle where the base is three, the base has length three, the height is length three, so it's going to be three times three, which is nine times one half, because three times three would give us the area of this entire square, but this triangle is half of that. So this right over here is going to be 4.5. And then what's this area in yellow? Well let's see, we have a triangle, its width here is four, its height is four, four times four is 16, which would be the area of this entire square, we take half of that, it's eight. Now we don't just add it to it, because once again, this is going to be negative area, the graph over here is below the t axis. So this we would say, this integral is going to evaluate to negative eight. Once again, why is it negative eight?