How to solve using substitution?

[lucky777loser777]

Would anyone mind helping me solve these using Substitution?

1) 2x = 1 - y
5x - 10y = -10

2) y – 2x – 1 = 0
-4y = 6 – 8x

3) -8x + 7y = 18
4y - 2x - 3 = 0

Thank you in advanced!

 

[Pal]

1) 2x = 1 -y
==> y = 1 - 2x
substitute it in 2nd equation, so
5x - 10 (1-2x) = -10
==>25x = 0
x = 0
so from above... y = 1

U can do others similarly...

 

[batmania101]

(I only did #1 to show you how to do substitution)

1) 2x = 1-y
5x-10y = -10

you can solve for x in the first equation and then plug it into the second equation to get a new equation in terms of y:

(2x)/2 = (1-y)/2

x = .5 - .5y

5x - 10y = -10 becomes

5(.5 - .5y) - 10y = -10
2.5 - 2.5y - 10y = -10
2.5 - 12.5y = -10
-12.5y = -12.5
y = 1

then plug y back into one of the equations to solve for x

2x = 1-1
2x = 0
x = 0

y=1
x=0