60m................50s.........590lei
30m................20s.........260lei/×2
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60m................50s..........590lei(-)
60m................40s..........520lei
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/ 10s. 70lei
10s=70lei
s=70÷10
s=7 lei
30m.............20×7.............260lei
30m+140=260lei
30m=260-140
30m=120
m=120÷30
m=4
R: Un kilogram de mere costă 4 lei, iar un kilogram de struguri costă 7 lei.