Can someone show me how to solve this algebra problem with more than one variable...?

Question

If a+3b= -1 and 2b+c=1 and a+c=5, how do I find out what a,b, and c are?

Answer 1

Because a+3b = -1 this means that a= -1 - 3b.

Because 2b + c = 1 this means that c=1-2b.

In the last formula, we replace a and c, so

a + c = 5 turns into -1 -3b + 1 - 2b = 5.

Then we have -5b = 5 so b = -1.

Because b=-1, a = -1 - 3*(-1) => a=2

and c = 3.