P = piersici; C = caise; R = prune
P + C = 1000 kg
C + R = 750 kg deci C = 750 - R
P + R = 1100 kg
P + C =1000 deci P + 750 - R = 1000 deci P - R = 250 deci P = 250 + R
P + R = 1100 deci 250 + R + R = 1100 deci 2R = 850 deci R = 425 kg (prune)
P = 250 + R = 250 + 425 = 675 kg (piersici)
C = 750 - R = 750 - 425 = 325 kg (caise)