Răspuns:
x/3 stejari plantati in prima zi
³⁾x-x/3=2x/3 rest
2x/3·1/3=2x/9 stejari plantati in a2a zi
⁹⁾x-(³⁾x/3+2x/9)=4x/9 noul rest
4x/9·1/3=4x/27 stejari plantati in a3a zi
⁹⁾x/3+³⁾2x/9+4x/27+²⁷⁾160=²⁷⁾x
9x+6x+4x+4320=27x
4320=27x-19x
x=4320:8
x=540 puieti in total
4·540:27=80 puieti s-au plantat a3a zi