Solve the system of equations by the substitution method.?

Question

{9x-18y=-9
{5x-5y=5

what is the solution?

Answer 1

5X - 5Y = 5
> x - y = 1
> y = x - 1

9x - 18y = -9
> 9x - 18(x-1) = -9
> 9x - 18x + 18 = -9
> -9x = -27
> x = 3

y = x - 1
= 3 - 1
= 2

x = 3; y = 2

Answer 2

you can substitute any variable at any equation. However the easier way is to take the second one:
5x-5y=5
then you choose for example x:
5x=5+5y
x=1+y
Now you substitute x in the first equation:
9x-18y=-9
9(1+y)-18y=-9
9+9y-18y=-9
9-9y=-9
-9y=-18
y=2
and since x=1+y, x=3
solution: x=3,y=2

Answer 3

5x = 5y + 5
x = y + 1

9(y + 1) - 18y = - 9
9y + 9 - 18y = - 9
- 9y + 9 = - 9
- 9 y = - 18
y = 2

5x - 10 = 5
5x = 15
x = 3

Answer is x = 3, y = 2

Answer 4

(for the bottom equation)
5x-5y=5
divide by 5
x-y=1
x=y+1

now substitute that in for the top equation:
9(y+1)-18y=-9
9y+9-18y=-9
-9y=-18 ( easier to change to positive but it doesnt matter )
9y=18
y=2

now substitue your y back into the equation ( x=y+1 )
x=(2)+1
x=3


now you have both x and y
y=2 and x=3

Answer 5

9x-18y=-9---------(1)
5x-5y=5------------(2)
From (2), x=1+y---------(3)
Substitute (2) into (1)
9(1+y) - 18y = -9
9+9y - 18y = -9
-9y = -18
y =2
From (3), x=1+2 = 3

Subtitution=Replacement

Answer 6

{9x-18y=-9
{5x-5y=5

{x-2y=-1...(1)
{x-y=1...(2)

(1)-(2):
-y=-2
y=2

Sub y=2 into (2)
x=3

{x=3
{y=2