Răspuns :
2×1+21supra21-3×1+14supra14⇒23supra21-17supra14 amplificacu14 amlifica cu 21
[tex]2 \frac{1}{21}- 3\frac{1}{14}= \frac{43}{21}- \frac{43}{21}=\bold{0} [/tex]