Answer :
a = 3b -c //we move 'b' to left side
a - 3b = - c // we move 'a' to right side
-3b = -a - c // we multiply by -1
3b = a + c // we devide by 3
b = (a + c ) / 3
other version => b = (1/3)a+ (1/3)c
a - 3b = - c // we move 'a' to right side
-3b = -a - c // we multiply by -1
3b = a + c // we devide by 3
b = (a + c ) / 3
other version => b = (1/3)a+ (1/3)c
