Question

La marginea satului am numarat 100 picioare de vaci si rate.stiind ca sunt 35 de capete aflati cate vaci si cate rate erau

Answer 1

V+R= 35 => V= 35-R
4V+2R = 100
4*(35-R)+2R = 100 
140-4R+2R = 100
40 = 2R 
R=20
V= 35-20=15

Answer 2

V-vaci R-rate V+r= 35 V= 35-R 4V+2R = 100 4*(35-R)+2R = 100 140-4R+2R = 100 40 = 2R R=20 V= 35-20=15