Question

Solve by substitution method: 4x + 3y = 13 x + y = 4

Answer 1

4x + 3y = 13
x + y = 4

^ is that it?

Answer 2

Well if:
4x + 3y = 13
x + y = 4

then we should isolate one of the variables first, in either equation. Lets start with the bottom and isolate (x):

x + y = 4

x = 4 - y

Now we have (x) in terms of (y), so we can go ahead and plug it in to the first equation:

4x + 3y = 13

4(4-y) + 3y =13

16 - 4y + 3y =13

16 - y = 13

-y = -3

y = 3

Now since we know what (y) is, we can use it to solve for (x):

x = 4-y

x = 4-3

x = 1

so y = 3 and x = 1