Question

Ex.10 la ii)????
Va rooog

Answer 1

Daca a+b=43 => a=43-b
b+c=15 => c=15-b
=> 7a+ 9b+ 2c= 7(43-b) + 9b + 2(15-b)
= 7*43 - 7b + 9b + 2*15 - 2b
= 301 + 9b - 9b + 30
= 301 + 30
=331