Chords Theorem
Congruent Chords are equidistant from the center of a circle, that means:
PO = EW and US = RU
then:
20n - 14 = -2(2n +1)
20n - 14 = -4n - 2
20n + 4n = -2 + 14
24n = 12
n = 1/2 or 0,5
And:
3m +2 = -m + 9
3m + m = 9 -2
4m = 7
m = 7/4 or 1,75