Question

a+2×b+3×c=330 a+c=70 a+b+2×c

Answer 1

A+c+2b+2c=330
70+2b+2c=330
2(b+c)=330-70
B+c=260:2
B+c=130

A+c=70
B+c=130
A+b+2c=70+130=200

Answer 2

a + 2 × b + 3 × c = 330 ;  a + c = 70

3 × c = c + 2 × c 

a + 2 × b + 2 × c + c = 330 
(a + c ) + 2 × ( b + c ) = 330 
70 + 2 ×(b + c) = 330 
2 × ( b + c) = 330 - 70 
b + c = 260 : 2 

b + c = 130 

a + b + 2 × c = 200
= a + b + c + c =  
= ( a + c) + ( b + c) =
=  70 + 130 =
= 200