Question

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Answer 1

a, b, c invers proportionale cu 1/2, 1/7 si 1/5

=> a/2=b/7=c/5

b=7a/2

c=5a/2

abc=1890

a×7a/2×5a/2=a³×35/4=1890

a³=216 => a=6

b=21

b=21c=15