The sum of the interior angles of a polygon can be calculated using the formula:

Sum of interior angles = (n - 2) 180 degrees,

where "n" is the number of sides of the polygon.

Given that the sum of the interior angles is 20 right angles, we can convert this to degrees since 1 right angle = 90 degrees:

20 right angles = 20 90 degrees = 1800 degrees.

Now, we can set up the equation and solve for "n":

(n - 2) 180 = 1800,

Divide both sides by 180:

n - 2 = 10,

Add 2 to both sides:

n = 12.

So, the polygon has 12 sides.