Răspuns:
={[(2·5+2)/5+(1·7+5)/7]·(4·8+3)/8}·21
=[(⁷⁾12/5+⁵⁾12/7)·35/8]·21
=[(84/35+60/35)·35/8]·21
= (144/35·35/8)·21
=18·21
=378
Explicație pas cu pas:
