Solve the system of equations using substitution and elimination -x - 9y= 16 10x+ 20y=20

y = and x =

Step-by-step explanation:

To solve simultaneous equations, you need to have the number in front of both x's or y's the same. (signs doesn't matter)

To get -x to -10x we simply  need to multiply the first equation by 10:

-x * 10 = -10x

-9y * 10 = -90y

16 * 10 = 160

-10x - 90y = 160

Now we can add the two equations:

-10x + 10x = 0

-90y + 20y = -70y

160 + 20 = 180

-70y = 180

70y = -180

7y = -18

y =

Now plug into the second equation:

10x + 20() = 20

10x - = 20

Move the over to the other side, making it a positive:

10x = 20 +

10x =

Divide both sides by 10:

x =

So y = and x =

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step-by-step explanation: