Question

What is the value of the x variable in the solution to the following system of equations?
7x - 2y = 21
4x + y = 57

21

-21

9

-9

Answer 1

First rearrange the top equation so you have x in terms of y and then sub this into the second equation.

Answer 2

so slope intercept form?

Answer 3

y=mx+b ?

Answer 4

yes

Answer 5

7x-2y=21
7x 7x

2y= 7x+21?

Answer 6

2y = 7x -21

Answer 7

Okay , then plug it into the 2nd equation??

Answer 8

yeah, then you will have an equation in terms of x only and can solve for x. Then take this value of x and plug back into the first equation to solve for y.

Answer 9

right right right , okay . So solving it would it be like this?
2y= 7x- 21
2 2 2
y= 7/2x - 10.5 ? but that would give it decimals .. and none of the options have a decimal , where am i messing up at .

Answer 10

I suggest you add the equations, then isolate why and find its value. After doing so, substitute it in y and you will get x. Hope I helped.

Answer 11

You could do it the other way round and solve the bottom one for y = 57 - 4x then sub this into the top one that way there will be no decimals. Either way you should end up with whole numbers by the end

Answer 12

so confused.

Answer 13

Ive tried literally every way you guys have told me and not gotten none of those 4 answers... /:

Answer 14

If you rearrange the bottom equation to get y=57 -4x then you can sub this back into the top one to get 7x - 2(57-4x) = 21

Answer 15

Okay i got
7x-114-8x=21

Answer 16

I dont know what to do from here .

Answer 17

Dont know how to do that.

Answer 18

You need to get all the x terms on one side and all the numbers on the other.
Add 114 to both sides then do 7x-8x for the left hand side.

Answer 19

Im just gonna guess the answer.Thanks for trying to help tho

Answer 20

lol fair enough

Answer 21

x=9 y = 21