Răspuns:
2) x·2/3=4/7
2x·7=4·3
14x=12=>x=12/14=>x=6/7
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2 si 1/3:x=2/5
7/3:x=2/5
x=7/3:2/5
x=7/3·5/2
x=35/6
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3) 3/5 din 2/7=3/5·2/7=6/35
12% din 4200=12/100·4200=12·4200:100=504
