Find a factored polynomial for the shaded area

Emma will roll two number cubes labeled 1 through 6. she will record the sum of the two numbers after each roll. she will roll the two cubes 540 times. how many times should emma expect the sum to equal 5?

Name each raycalculation tip: in ray "ab", a is the endpoint of the ray.

Asap! i'm not good math and i'm lost.