Which of the following ordered pairs represents the solution to the system given below?

2x + y = 20
4x − 2y = 40

(10, 0)
(0, 10)
(4, 2)
(10, −10)

Question

Which of the following ordered pairs represents the solution to the system given below?

2x + y = 20
4x − 2y = 40

 (10, 0)
 (0, 10)
 (4, 2)
 (10, −10)

igreen · Answer

You can use substitution to solve.

igreen · Answer

$\sf 4x - 2y = 40$

Subtract 4x to both sides:

$\sf -2y = -4x + 40$

Divide -2 to both sides:

$\sf y = 2x - 20$

Now plug in $\sf 2x - 20$ into the first equation for $\sf y$ and solve for $\sf x$, then plug that into any of the two equations to find $\sf y$.

igreen · Answer

Can you do that?

automaticloveletter · Answer

I'd rather have you walk me through it can you?

igreen · Answer

Okay, we have:

$\sf 2x + (2x - 20) = 20$

Can you solve that for $\sf x$?

automaticloveletter · Answer

10

automaticloveletter · Answer

So it's 10, ?

vocaloid · Answer

continuing from here, we know that x = 10 since you just solved for it

let's take one of our original equations

2x + y = 20
let x = 10 and solve for y