Question

Stind ca.2a+8b=20 afla a+4b

Answer 1

la A) 2a+8b=20| :2 =>a+4b=10
B)9a+12b+7=28| :3 => 3a+4b=(28-7):3=> 21:3=7
C) 4a+10b-3=27| :2=> 2a+5b=30:2=15
D) 7a+14b+21=105| :7=> a+2b=(105-21) :7=84:7=12| inmultim cu 3
=> 3a+6b=36
E) 5a+15b+10z=30| :5 => a+3b+2z=6 inmultim cu 3=> 3a+9b+6z=18
F) 6a-12b-5=67| : 6=> a-2b=(67+5):6=72:6=12
a-2b=12| inmultim cu 5=> 5a-10b=60+13=73