cu plan de rezolvare

r + g = 20 => r = 20 - g
10r - 2g = 176
10(20 - g) - 2g = 176
200 - 10g - 2g = 176
200 - 176 = 10g +- 2g
24 = 12g
g = 2 gresite
r = 18 rezolvate