notam cu x nr. de Km parcursi in prima zi in cele 4 zile a parcurs: x+x+25+x+50+x+75=310Km 4x+150=310 4x=310-150 x=160:4 x=40 Km parcurge in prima zi 40+25=65 Km a doua zi 65+25=90 Km a treia zi 90+25=115Km a treia zi 50+65+90+115=310Km in total (verificare)