Geometry
posted by HELP!!! URGENT .
the number of sides in 2 regular polygons is in the ratio 5:4 an the difference between their angles is 9^o. Find the number of sides in the polygon

The internal angle each corner of a regular polygon is 180  360/n degrees.
Let N be the number of sides of polygon with fewer sides. The other polygon then has 5N/4 sides.
180  360/N  [180  360*0.8/N] = 9
360/N + 288/N = 9
72/N = 9
N = 8
The other polygon has 10 sides.
The internal angles are 135 and 144 degrees.