Eu parantezele nu le pun pătrate sau acoladele le pun simple le transformi tu
1+(2(3+5a-20):6)*7=8
1+(2(-17+5a):6)*7=8
1+ 2(-17+5a) supra 6 *7=8
1+ -17+5a supra 3 *7=8
1+ 7(-17+5a) supra3 =8
1+ -119+35a supra 3 =8
3*1+3* -119+35asupra 3 =3*8
3-119+35a=24
-116+35a=24
35a=24+116
35a=140
a=4
Coroana ?
