Răspuns:
a+b+c=68
a=c+12=>c=a-12
a=2b=>b=a/2
a+a/2+a-12=68 aplific
2a+a+2a-24=136
5a=136+24
a=160:5
a=32 km parcurge in prima zi
32:2=16 km parcurge a2a zi
32-12=20 km parcurge a3a zi
a + b + c = 68
a = 12 + c
a = 2 × b
c = a - 12
b = a : 2
a + a : 2 + a - 12 = 68 | × 2
2 × a + a + 2 × a - 24 = 136
5 × a - 24 = 136
5 × a = 136 + 24
5 × a = 160
a = 160 : 5
a = 32
b = 32 : 2
b = 16
c = 32 - 12
c = 20
