👤

a+b=7
b+c=10
a+3b+2c =?


Răspuns :

a+3b+2c = (a+b ) + 2x(b+c0
= 7 + 2x10
= 7+20
=27
a=7-b
7-b+3b+2c=?
7+2b+2c=?
7+2(b+c)=?
7+20=?
27