Question

Solve the system of equations using substitution and Elimination

Answer 1

Greetings!

Answer:

y = $\frac{-18}{7}$ and x = $\frac{50}{7}$

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 = $\frac{-18}{7}$

Now plug $\frac{-18}{7}$ into the second equation:

10x + 20($\frac{-18}{7}$) = 20

10x - $\frac{360}{7}$ = 20

Move the $\frac{360}{7}$ over to the other side, making it a positive:

10x = 20 + $\frac{360}{7}$

10x = $\frac{500}{7}$

Divide both sides by 10:

x = $\frac{50}{7}$

So y = $\frac{-18}{7}$ and x = $\frac{50}{7}$

Hope this helps!