Question

how do you get the answer to (x-y=-5
(-x+4y=10

Answer 1

all i know is you use substitution

Answer 2

add the two equations and post what you got.

Answer 3

what do you mean by add them

Answer 4

steps:
x-y=-5
-x+4y=10
despejas x
x=-5+y
5-y+4y=10
3y=5
y=5/3

ahora en x-y=-5
x-(5/3)=-5
x=-10/3

Answer 5

x-y = 5 -------> Equation 1
-x+4y = 10 ------------> Equation 2

Add equations 1 and 2

Answer 6

oh also if it helps im only in 8th grade

Answer 7

By `add' he means basically add each part (the parts with x, the parts with y, and the parts with neither) in each equation, and see what the resulting equation is.

Answer 8

No shadow fiend. The problem is different. These answers were getting jumbled up, with another post

Answer 9

so -x=4y=5

Answer 10

if (3 x 4 ) = 12
and (5 x 4) = 20,
then when we add the equations we get
(3 x 4) + (5 x 4) = 12 + 20
12 + 20 = 32
32 = 32.
so it checks out. similarly add your equations,

Answer 11

meaning
(x-y) +(-x+4y) = -5 + 10

Answer 12

wow this is even more confusing now

Answer 13

what is confusing about this?

Answer 14

So, norbeybarajas gave another good answer, both will lead you to the same path. If you add the two equations up, you'll see that the x disappears and you can solve for y.

Answer 15

ok thx for the answers not confusing any more

Answer 16

do you understand that if
a = b
and c = d,
then a+c will be equal to b+d?

Answer 17

yeah

Answer 18

Rock it. Make sure you click `good answer' next to the answers that were helpful :)

Answer 19

alright can do

Answer 20

okay, so that is exactly what I did in your equation.
I saw that one equation had x and the other equation had -x.
so I knew that if i added them up, the x will cancel each other out, leaving me only with y.
which means i can solve for y.

Answer 21

yeah

Answer 22

once I solve for y, all i need to do is substitute it in one of the equations and get x.