Răspuns :
= {[ 14 × 6 - ( 72 - 72)] × 5 } × 2
=[ ( 14 × 6 - 0 )× 5] × 2
= ( 84 × 5) × 2
= 420 ×2
= 840
=[ ( 14 × 6 - 0 )× 5] × 2
= ( 84 × 5) × 2
= 420 ×2
= 840