Explanation:
We are going to start by working out the interior angles so first of all to work out the interior angle we used the formula: num of sides - 2 * 180 for the sum of degrees in a shape.
Lets test this formula.
Lets say we have a square it has 4 sides 4-2 = 2 *180 = 360 this is correct,meaning we can trust this formula.
Now lets put it to use.
Octagon has 8 sides - 2 = 6.
6 * 180 = 1080
Pentagon has 5 sides - 2 = 3
3 * 180 = 540
Another Pentagon 5 sides - 2 = 3
3 * 180 = 540
We have to find out a single angle because it is one side that joins to the other, also if it is a perfect fit then all the single angles must add up to 360.
1080/8 sides = 135 degrees
540 / 5 sides = 108 degrees
540 / 5 sides = 108 degrees
We add these up,
135 + 108 + 108 = 351 which cannot be a possible fit because we need 360 degrees.
Hope this helps