Question

How do you solve the following linear system: # 2x + 4y = 7 , x + y = 3 #?

Answer 1

From the second expression you can derive that `y=3-x` (by subtracting `x` from both sides.

Explanation:

Now you can substitute (=replace) every `y` in the first expression by this value:
`->2x+4*(3-x)=7` work away the brackets:
`->2x+12-4x=7` put together and subtract 12 on both sides:
`->2x-4x=7-12->-2x=-5`

`->x=2 1/2->y=3-2 1/2=1/2`

Just to make sure, you will want to put the answers back into the question.