10+ 10 + s = 180

5a + 3c + 2s = 500
a = 10c

10 + 10 + s = 180

S = 180-20 = 160

a = 10c.
5*10c + 3c + 2*160 = 500
50c + 3c + 320 = 500
53c = 500-320 = 180
C = 3.396

a = 10c = 10*3.396 = 33.96