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Un drumet a mers in prima zi 30 % din drum , a doua zi 30℅ din rest si a treia zi restul , adica cu 7 km mai mult decat a doua zi . Cati km are drumul ?

Răspuns :

1 zi:[tex] \frac{30}{100} [/tex] x drum
2 zi:[tex] \frac{30}{100} [/tex] x(drum - [tex] \frac{30}{100} [/tex] x drum)
3 zi:7 + [tex] \frac{30}{100} [/tex] x(drum - tex] \frac{30}{100} [/tex] x drum)
1zi +2zi+3zi=drum

[tex] \frac{30}{100} [/tex] x drum + [tex] \frac{30}{100} [/tex] x(drum - [tex] \frac{30}{100} [/tex] x drum) + 7 + [tex] \frac{30}{100} [/tex] x(drum - [tex] \frac{30}{100} [/tex] x drum)=drum