Răspuns:
2x/7 → prima zi
⁷⁾x-2x/7=(7x-2x)/7=5x/7 rest
5x/7·1/4= 5x/28 → a2a zi
⁴⁾2x/7+5x/28+²⁸⁾75=²⁸⁾x
8x+5x+2100=28x
2100=28x-13x
2100=15x
x=2100:15=>x=140 km lungimea drumului
verificare:
2·140:7=40 km a parcurs prima zi
140-40=100 km rest
100:4=25 km a parcurs a2a zi
40+25+75=140 km lungimea drumului
